260 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



irreconcilable differences of opinion. I shall not enter the interminable 

 and unprofitable " test cell " controversy, for however the case may be in 

 other tunicates, the deeply stained wandering amoeboid bodies which are 

 found among the young eggs of salpa are certainly migratory follicle 

 cells. 



There is, however, another more important subject of controversy 

 which we must soon take up the fate of those follicle cells, or, to use 

 Salensky's term, Kalymmocytes, which, at a later stage, migrate into the 

 substance of the growing embryo of salpa. 



It is well known that this observer has been led by his minute 

 researches on salpa and pyrosoma to the view that the kalymmocytes 

 contribute to the cellular structure of the embryo, so that the tissues of 

 its body are, in part at least, derived from the follicle and not from the 

 fertilized egg. 



In this connection all new facts regarding the fate of any of the 

 migratory follicle cells of salpa become important, and for this reason I 

 shall quote a few observations from among the many which are on 

 record, to show that my view of the way the egg of salpa is nourished is 

 in accord with our knowledge of the history of the egg in many other 

 animals. 



Seeliger says (Eibildung und Knospung von Clavelina lepadiformis, 

 Sitzb. der k. Akad. der Wissensch. LXXXV, I, 1882, p. 6) that only one 

 cell in a certain area of the ovary of clavelina becomes an egg, while 

 the cells around it aid in its progress towards completeness and lose 

 themselves in it ; and his paper is fully illustrated with figures to show 

 the migration of the cells around the egg into its substance, and their 

 degeneration to supply the material for the yolk. 



Beddard says (Quart. Journ. Mic. Sc. XXX, p. 471) that in the 

 majority of the oligocha3ta the ovum is detached from the ovary and 

 falls into the egg sac in company with a number of germinal cells, 

 which probably serve for the nutrition of the ovum. 



Shelden says (Quart. Journ. Mic. Sc. XXX) that in Peripatus Nova3- 

 Zealandica there is a small amount of yolk present in the young ovarian 

 eggs, in the form of scattered spheres throughout the protoplasm of the 

 ovum, and that there are also in the protoplasm small, round or oval 

 nuclei, which in every respect resemble those of the follicle, so that it 

 seems almost certain that these must have migrated from the latter, a 

 process which would be simple in the absence of any separation between 

 the ovum and the follicle. Hamann says (Anatomie der Ophiuren und 



