220 
ZOOLOGY: R. GOLDSCHMIDT 
SOME EXPERIMENTS ON SPERMATOGENESIS IN VITRO 
By Richard Goldschmidt 
(of the Kaiter Wilhelm Institut fiir Biologic. Berlin) 
OSBORN ZOOLOGICAL LABORATORY, YALE UNIVERSITY 
Presented to the Academy. March 3, 1915 
Unforeseen circumstances that forced me to interrupt my normal work 
offered a chance for trying some experiments, that I have had in mind 
for some time, to apply the method of tissue culture to the study of 
sex-cells with the purpose of rendering the history of these cells accessible 
to an experimental analysis. The results obtained in this direction dur- 
ing the past winter constitute of course nothing more than the first steps 
into a very promising field of research. For the experiments the sperm- 
cells of the moth, Samia cecropia L., were used. The method of cultiva- 
tion is simply Harrison's method. By tearing the testis of the pupa the 
thousands of sperm folhcles (spermatocysts) are isolated and can easily 
be mounted in a hanging drop of haemolymph. Naturally the whole 
procedure must be carried out strictly aseptically. In November most 
of the follicles contain spermatogonia or young spermatocytes during 
the growth-period. They could be kept alive in the cultures about 
three weeks, and during this time a great many follicles finished the 
process of spermatogenesis up to the full grown spermatozoa under the 
eye of the observer. The time required depends, as was to be expected, 
upon the temperature. It seems that the stages from the spermatogonia 
up to the maturation divisions need weeks for their development but 
maturation and spermatogenesis occur in a few days even in one day 
when kept warm. The most striking, although in no way surprising 
result of the observations is the complete harmony between the facts 
as observed in the living cell and those described from preserved speci- 
mens. The formation of the axial filaments in the young spermatocytes 
and their subsequent behavior, as well as the mitochondria and their 
distribution during the maturation divisions, could readily be followed. 
The interesting and hitherto unobserved behavior of the axial filaments 
in the formation of the regular sperm-bundles could also be made out. 
In addition interesting observations were made upon the behavior of 
the follicle membrane after the death of the sperm cells. At this time 
an extensive outgrowth of these cells begins, forming a kind of tissue 
which grows luxuriantly for some weeks more. 
The observations made upon normal spermatogenesis suggested the 
hypothesis that the specific changes undergone by a sperm cell in its 
development into that strange thread-like spermatozoon may be due 
