212 
FOURTEENTH REPORT. 
THE ORIGIN OF THE GERM CELLS IN THE TOADFISH. 
(OPS ANUS TAU.) 1 
BY EMORY W. SINK. 
The following is a preliminary account of the problem of the Early 
History of the Germ Cells in Teleost Fishes.- This subject in general 
is one to which considerable attention has been given by a score of 
workers in recent years. It is of interest not only because of its bear- 
ing on morphological development but especially because of its relation 
to problems of heredity. Whether or not the germinal material is 
handed down from one generation to the next in an unchanged condi- 
tion, or whether the germ plasm ever arises from somatic cells of the 
embryo, is a question which is fundamental in its bearings on genetics. 
The Invertabrates have been a very favorable group for this study 
and considerable work has been done on them with interesting results. 
The Vertebrates likewise have been employed for similar investigations, 
but for various reasons the problem has been more complex, so that 
the results are not as far reaching as those from a study of the Inverte- 
brates. 
The fact that the germ cells are found in various parts of the Verte- 
brate embryo during development and that they actively migrate or 
are passively carried to a definite region of the embryo where the sex 
glands form, is a phase of the problem so complex that many theories 
have been advanced to account for the process. 
Three views have been held in regard to the origin of the germ cells 
in Vertebrates. The first known as the Germinal Epithelial Theory was 
advanced by Waldever in 1870. This investigator maintained that the 
germ cells arose from epithelial cells in the region (germinal ridge) of 
the embryo where the future sex glands formed. This view was plaus- 
ible at the time and quickly accepted by many embryologists, for it 
was in this ridge that the germ cells could first be distinguished. The 
fact that they are so conspicuous in this region, led many observers 
to think that they originated there, but the method of this origin has 
not as yet been satisfactorily explained. 
The second view proposed by Ruckert and Van Wijhe in 1888-9 main- 
tains that the germ cells originate from a definite portion of the seg- 
mental mesoblast and are later transported during development to the 
germinal ridge. This view has been subjected to much speculation but 
is not accepted by most workers of the present decade. 
The third view, which is probably the correct one, is based not entire- 
ly on observation, but also on the assumption that the germ cells are 
set aside or segregated from (lie somatic cells at a very early stage of 
'The work on this investigation was carried on in the Zoological Laboratory of the University of 
Michigan under the supervision of Prof. Jacob E. Reighard. 
2 For a good resume of the recent work on this subject, reference may be made to Gideon S. Dodd’s 
paper on the “Segregation of the Germ-Cells of the Teleost, Lophius.” Journal of Morphology, Vol. 
21, No. 4. 
