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178 



SCIENCE 



[N. S. Vol. XLIV. No. 1127 



itself has come to an end, but that the work 
of the author is finished too. There are many 
who can carry forward investigations and com- 
plete new discoveries, but there are very few 
who are made competent by their thorough 
scholarship to understand, and through their 
delightful style to explain, the evolution of 
scientific thought from one age to another. 
Percy M. Dawson 



SPECIAL ARTICLES 

THE PROCESS OF FEEDING IN THE OYSTER 

A valuable contribution to knowledge of the 
ciliary mechanisms of Lamellibranch mollusks 
has been made by James L. Kellogg in Vol. 26, 
No. 4, of the Journal of Morphology. 

In this paper Dr. Kellogg brings together, 
with numerous illustrations, his observations 
on the ciliary tracts of structures found within 
the mantle chamber of thirty-one species of 
lamellibranchs. 

In each case the observations were made on 
the animal after one of the valves of its shell 
had been removed, and the presence and direc- 
tion of ciliary currents were determined by 
means of powdered carmine, fine black sand or 
masses of diatoms, deposited upon the parts 
under observation. 

Among the several conclusions at which Dr. 
Kellogg arrives as a result of his study con- 
cerning the activities and functions of these 
tracts of cilia, the following, published on 
pages 699 and 700, are those to which the " oral 
exceptions," referred to by Dr. Kellogg on 
page 640, have been taken and they are the 
ones also which will be called in question in 
this paper: 

1. Volume alone determines whether the collected 
foreign matter that reaches the palps shall pro- 
ceed to the mouth or shall be sent from the body 
on outgoing tracts [of cilia]. 

2. A Lamellibranch is able to feed only when 
waters are comparatively clear — when diatoms are 
brought to the gill surfaces a few at a time. In 
muddy waters, all suspended particles, of whatever 
nature, are led to outgoing tracts. 

3. There is no selection or separation of food or- 
ganisms from other water-borne particles. 

4. The direction of the beat of cilia is never 
changed. 



The exceptions taken to these statements 
were not based, as Dr. Kellogg states, on the 
fact that the waters over Chesapeake oyster 
beds are normally muddy for long periods of 
time or upon the fact that the stomach con- 
tents of oysters always contain a larger volume 
of sand than of food organisms, although both 
of these facts are difficult to explain on the 
Kellogg theory, but they are based primarily 
upon the results of experiments, to be described 
later, which show that oysters can and do feed 
rapidly and continuously in waters that are 
turbid with sediment. 

Before passing to a consideration of the re- 
sults of these experiments, however, which bear 
directly upon the first and second only of Dr. 
Kellogg's conclusions (as numbered in this 
paper), reference may be made to the findings 
of other observers not in agreement with those 
of Dr. Kellogg, which indicate that the con- 
clusions numbered (3) and (4) were possibly 
drawn from an insufficient basis of observation 
or that the methods of study employed by Dr. 
Kellogg were not designed to reveal all of the 
activities of the ciliary mechanisms of lamelli- 
branchs. 

REVERSAL OP CILIA AND POOD SELECTION 

In Stentor, Schaeffer 1 has shown that there 
is a selection of food particles brought about 
by changes in the beat of the cilia of the pouch 
and funnel, certain particles being rejected by 
a localized reversal of the cilia. He also found 
that the behavior of the animal toward food is 
not the same when it is in a condition of 
hunger as when in a condition of satiety. 

Stentor is not an isolated example of proto- 
zoan possessing the power of food selection and 
rejection exercised through the control of the 
ciliary mechanism of the mouth region. Nu- 
merous other cases might be cited. 

Oases of reversal of cilia are also reported 
among metazoan animals, Parker 2 having 
found that in Metridium the cilia on the lips, 
which normally beat outward, can be made to 

i Asa Arthur Schaeffer, ' ' Selection of Food in 
Stentor cwruleus," Jour. Exp. Zool., 1910. 

2 G. H. Parker, ' ' The Eeversal of Ciliary Move- 
ments in Metazoans, " Am. Jour, of Physiology, 
Vol. XIII., 1905. 



August 4, 1916] 



SCIENCE 



179 



reverse by stimulation -with pieces or the juices 
of crab meat, these ciliary tracts thus consti- 
tuting a mechanism through which the feed- 
ing process can be controlled. 

In this paper Parker refers also to a num- 
ber of papers, not easily available to the writer 
and not referred to by Dr. Kellogg, in which 
the reversal of ciliary movement in metazoans 
has been observed. Of special interest in this 
connection are those by Engelmann and others 
in which the reversal of cilia of the palps of 
lamellibranchs is described. 

The only positive evidence I can offer for the 
conclusion that the oyster is able to select food 
is that afforded by a microscopic examination 
of its stomach contents. The various species 
of diatoms there found are not present in the 
same relative proportions as they exist in speci- 
mens of water collected in the vicinity of the 
bed from which the oyster fed. Furthermore, 
certain species of diatom (for example, Bhizo- 
solenia), abundant in salt water, are seldom 
found in the alimentary tract of the oyster. 
The absence of these diatoms from the alimen- 
tary canal can hardly be due to their spiny 
structure because their size is not sufficiently 
great to prevent their being carried by ciliary 
currents or entering the mouth. 

The observations that have been made of the 
reversal of the beat of cilia in both protozoa 
and metazoa, and of the ability of various ani- 
mals to so control the movement of the cilia 
as to accept or reject food particles presented 
to them, at least suggest the possibility that 
the oyster may also have some power of food 
selection and that reversal of the cilia of cer- 
tain tracts on the palps, resulting perhaps 
from their stimulation directly or indirectly 
by food particles, may be the mechanism by 
which the selection is effected. 

"Why, then, if a reversal of cilia and selec- 
tion of food takes place in lamellibranchs, did 
so good an observer as Dr. Kellogg fail to see 
the reversal process? To me it seems clear 
that it was due to the fact that the animals on 
which he made his observations were, in every 
case, in a mutilated condition. In the case of 
his experiments on the oysters the shell was 
first removed and in its removal the adductor 



muscle was cut and the visceral ganglion, 
which is embedded in this muscle, was neces- 
sarily severely injured. Under such a condi- 
tion of shock normal behavior is not to be 
expected, especially in the case of activities 
that may be subject to nervous control. The 
history of the animals experimented upon by 
Dr. Kellogg, whether they were in a state of 
hunger or satiety, was also unknown. 

EXPERIMENTS 

During the years 1909 and 1910 oysters 
planted on beds located in Buzzards Bay re- 
mained poor and the death rate among them 
was unusually large. Coincident with and fol- 
lowing the same period, dredging operations 
were carried on in the vicinity of certain of 
these oyster beds which caused an unusual 
amount of sediment to be carried from the 
dredges across the oyster beds with the rising 
tides. 

The oyster planters readily imagined that 
the poor condition and death of their oysters 
were in some way causally connected with this 
sediment in the water and they brought suit to 
recover their losses, with generous interest, 
from those responsible for the dredging opera- 
tions. 

During this litigation it has been the oral 
contention of Dr. Kellogg that, since the 
oysters planted on the beds located near the 
operating dredges were exposed on rising tides 
to unusually turbid water and since food-bear- 
ing sediment was therefore entering the mantle 
cavity of the oysters during these intervals in 
unusual abundance, the oysters were underfed 
and starved because the ciliated food-collecting 
mechanism of the palps must, under such con- 
ditions, transport the food-bearing material 
away from instead of to the mouth. 

The ciliated food-collecting mechanism of the 
oyster is so constructed, according to the theory 
held by Dr. Kellogg, that it can transport food 
material to the mouth only when the food par- 
ticles reach the ciliated tracts few at a time, 
for when they reach the palps more rapidly 
they are seized automatically by the cilia of 
outgoing tracts. It is an important part of his 
theory that the direction of the beat of the 
cilia composing the food-transporting mechan- 



180 



SCIENCE 



[N. S. Vol. XLIV. No. 1127 



ism is non-reversible, hence his conclusion in 
this case that the oysters starved in the pres- 
ence of an abundant supply of food. Although 
starving, the oysters were powerless to prevent 
the rejection of food material for the remark- 
able reason that the food material was reach- 
ing their feeding mechanism in embarrassing 
abundance. 

It was not contended that the sediment was 
distasteful, for, in the organization of an ani- 
mal with such a purely automatic feeding 
mechanism, what possible place could be found 
for so useless a thing as a sense of taste ? 

To test the validity of this contention the 
following experiments were carried out on the 
oyster beds where the oysters were said to 
have died from starvation, at a time when the 
waters were roiled and turbid from the opera- 
tions of nearby dredges. 

A considerable number of oysters of uniform 
size were first gathered from a bed far re- 
moved from the scene of the dredging opera- 
tions. Five of them were immediately opened, 
their stomach contents removed and preserved 
in a vial for future study and analysis. The 
remaining oysters were thoroughly cleansed of 
all foreign material and stored for three days 
in a cool damp place. Twice each day they 
were placed for an hour in filtered sea water in 
order that they might expel from their shells 
the accumuated excreta. They were allowed 
to take no food. At the end of the third day of 
fasting, the primary object of which was to 
remove from the alimentary canal all previ- 
ously ingested food material, the oysters were 
taken to a selected point on one of the oyster 
beds over which the sediment from the dredges 
was being carried by the rising tide and there, 
after five of them had been opened and their 
stomach contents removed, placed upon the 
bqttom. 

To facilitate depositing the oysters upon 
and removing them from the bottom, they 
were placed in a coarse-meshed wire tray to 
which cords were attached. 

At the end of an hour from the time the 
oysters were deposited upon the bottom in the 
turbid water the tray was lifted for a moment, 
the stomach contents of five of the oysters were 



removed, and the tray with the remaining 
oysters returned to the bottom. At the end of 
the second hour this process was repeated and 
also at the end of the third hour. When the 
experiment was over the unused oysters were 
left upon the bottom in the tray for fourteen 
days to note the effect of the sediment upon 
them with the result that all thrived and made 
perceptible growth of shell. 

The microscopic examination and estimate 
of the number of food organisms in the stom- 
ach contents taken from this series of oysters, 
which was made according to the "Rafter 
cell " method, resulted as follows : 
Each oyster estimated to contain, when collected 

August 19, 10.30 A.M., 18,500 food partieles. 
Each oyster estimated to contain, after fasting till 

August 22, 1.30 p.m., 8,250 food particles. 
Each oyster estimated to contain, after feeding 1 

hour, August 22, 2.30 p.m., 11,500 food particles. 
Each oyster estimated to contain, after feeding 2 

hours, August 22, 3.30 p.m., 17,750 food partieles. 
Each oyster estimated to contain, after feeding 3 

hours, August 22, 4.30 p.m./? 

A second experiment in every way similar 
to the first, except that the oysters were sub- 
jected to a preliminary fast of four instead of 
three days' duration, was carried out between 
August 31 and September 4, 1911. The esti- 
mates of the stomach contents of the oysters 
used in this experiment are as follows: 
Each oyster estimated to contain, when collected, 

August 31, 10 a.m., 12,125 food organisms. 
Each oyster estimated to contain, after fasting till 

Sept. 4, 1 p.m., 2,850 food organisms. 
Each oyster estimated to contain, after feeding 1 

hour, Sept. 4, 2 P.M., 10,250 food organisms. 
Each oyster estimated to contain, after feeding 2 

hours, Sept. 4, 3 p.m., 16,500 food organisms. 

RESULTS AND CONCLUSIONS 

The results of these experiments show con- 
clusively that oysters can and did feed actively 
in waters that were turbid with sediment, a 
fact that is in direct opposition to Dr. Kel- 

3 The food material removed from the stomachs 
of the oysters which had been feeding for three 
hours in the roiled water was so densely crowded 
with sediment that it was impossible to make the 
diatom counts necessary for an estimate of the 
total number of food organisms. 



August 4, 1916] 



SCIENCE 



181 



logg's conclusion, numbered (2) in this paper, 
and one that casts doubt upon the correctness 
of the three other conclusions herein discussed. 

It is my belief that the results of the ex- 
periments and observations herein described 
when considered in connection with the obser- 
vations of other investigators on various spe- 
cies of lamellibranchs and on various protozoa 
and metazoa, afford a satisfactory basis for 
concluding that the oyster is not the helpless 
automaton Dr. Kellogg makes it out to be, but 
that it possesses sufficient control over its cili- 
ary feeding mechanism to prevent its starving 
in the presence of water-borne food material, 
even though the food particles and associated 
sand grains may be carried to its gills and 
palps in bewildering abundance. 

This control of the feeding mechanism and 
the ability to select food may conceivably be 
exercised through control of the direction of 
the effective beat of the cilia of certain tracts 
on the palp surfaces and, since reversal in the 
stroke of cilia on the palps (nebenkiemen) of 
lamellibranchs has actually been observed by 
Engelmann and others, and since selection and 
rejection of foreign particles through control 
of ciliary movement have been observed in 
various animals (Stentor, Metridium, etc.), we 
may well expect to find that the oyster exer- 
cises control over its feeding processes through 
ability to change the direction of the effective 
stroke of the cilia of certain tracts on its palps. 

Caswell Grave 
Johns Hopkins University, 
Baltimore, Md. 



THE AMERICAN ASSOCIATION OF 

MUSEUMS 
The American Association of Museums held its 
eleventh annual meeting in Washington, D. 0., 
May 15-18. The opening session was devoted to 
the transaction of business, and to a special report 
by Secretary Paul M. Eea on the "Condition and 
Needs of American Museums." This report sum- 
marized the work of the association during the 
past ten years, reviewed the studies of American 
museums which have been made on behalf of the 
association, and outlined the work which might be 
undertaken for the furtherance of museum de- 
velopment. 



The evening of May 15 was devoted to a supper 
in celebration of the decennial of the American 
Association of Museums. Following this supper 
the presidential address was given by Dr. Oliver 
C. Farrington on ' ' Some Eelations of Art and Sci- 
ence in Museums." The remainder of the evening 
was occupied with informal remarks by members 
of the association. This session was presided over 
by Dr. W. J. Holland, of the Carnegie Museum, 
who was one of the founders of the association 
and its third president. 

At the morning session on May 16 a group of 
papers was presented reporting progress in a con- 
certed experiment by several museums in the use 
of museums for instruction in the history of civili- 
zation. This symposium was arranged by Miss 
Anna D. Slocum, acting on behalf of the associa- 
tion in cooperation with the Woman's Education 
Association of Boston. The titles of the papers 
were as follows: 

"A Study of Nations through the Museum," 
by Miss Anna D. Slocum. 

"History Study and Museum Exhibits," by 
Miss Delia I. Griffin. 

"Museum Stories of Art and Civilization," by 
Miss Margaret E. Sawtelle. 

"The Museum Story as an Introduction to His- 
tory," by Mrs. Laura W. L. Scales. 

"Teaching History in the Museum," by Mrs. 
Agnes L. Vaughan. 

"The Museum and the School," by Miss Lotta 
A. Clark. 

Other papers presented at this session were "A 
Museum Game," by Miss Eva W. Magoon, and a 
paper on the "Development of the N. W. Harris 
Publie School Extension of the Field Museum of 
Natural History," by Mr. S. C. Simms. Miss 
Viola M. Bell, of Teachers College, Columbia Uni- 
versity, presented by invitation a paper on "Re- 
lations of Domestic Science Teaching to Mu- 
seums." Following these papers the association 
proceeded to the election of officers with the fol- 
lowing result: 

President, Henry R. Howland, Buffalo Society 
of Natural Sciences. 

Vice-president, Newton H. Carpenter, Art Insti- 
tute of Chicago. 

Secretary, Paul M. Rea, The Charleston Museum 
(S. C). ■ . 

Treasurer, W. P. Wilson, The Philadelphia Mu- 
seums. 

Assistant Secretary, Laura L. Weeks, The Charles- 
ton Museum (S. C.) 

The retiring president, Dr. Oliver C. Farrington,