34 
WILLIAM KEITH BROOKS 
pore, and the origin of the digestive tract. The technique necessary 
for the successful sectioning of such small bodies as snail eggs 
had not been developed at this time. Brooks' observations were 
therefore made exclusively on material studied in toto, and it is 
interesting to find that this method of study led him into several 
serious errors. In his paper on the ^'Acquisition and Loss of a 
Food Yolk in Molluscan Eggs," Brooks devoted much attention 
to what is now known as the yolk lobe, or polar lobe, which he 
regarded as a food yolk which is disappearing in some forms, while 
in others it is being acquired. In a brief paper on the ''Develoi>- 
ment of the Digestive Tract in Mollusks" he reiterates his mis- 
taken view that in gasteropods and lamellibranchs the blastopore 
is converted into the shell gland. Not until 1908 did he return to 
the gasteropods, publishing in that year in association with Bartgis 
McGlone, one of his students, a paper on the origin of the lung 
in Ampullaria. 
Brooks has two papers on the development of cephalopods pub- 
lished in 1880. His important conclusions in these papers deal 
with the homologies of the cephalopod yolk sac, siphon, and arms. 
Numerous publications deal with the development and propa- 
gation of the oyster. In 1878, during the first session of the Chesa- 
peake Zoological Laboratory, he attempted to find young oysters 
in the gills of the female, as had been described for the European 
oyster, but without success. In May, 1879, he went to Crisfield, 
Maryland, the center of the oyster industry on the Chesapeake, 
and settled down to study the problem of the development of 
the oyster. He soon learned that artificial fertilization was possi- 
ble, and that the American oyster normally discharges its eggs 
and sperm into the open water, where the processes of fertiliza- 
tion and development go on independently of the parents. The 
results of his embryological studies on the oyster were published 
in full in a report to the Maryland Fish Commission (1880). 
This paper was very favorably received and was republished 
in whole or in part in many American and European journals. 
In recognition of the importance of. this work he was awarded a 
medal by the Societe d'Acclimatation of Paris. 
