DAVIS: SPERMATOGENESIS. 125 
chromatin occurs, the term has been used in a wider sense to apply 
to the entire series of phenomena which are concerned in the conjuga- 
tion of the chromosomes, and especially to the stage at which the 
reduced number of chromosomes is first apparent. Moore himself 
(farmer and Moore :05) has used the term in this somewhat modified 
sense, where it is equivalent to his ‘‘contraction figure,’ and has. 
defined it as follows: —‘‘Synapsis represents that series of events which 
are concerned in causing the temporary union in pairs of premaiotic 
chromosomes, previously to their transverse separation and distribu- 
tion, in entirety between two daughter nuclei.” Used in this sense 
the term will apply, in the case of the male germ cells at least, to the 
greater part of the growth period, and especially to the stage of the 
polar spireme. In fact, an examination of the literature leads to the 
conclusion that the occurrence of the polar loops is the most character- 
istic phenomenon of the synaptic period, and while in the present 
stage of our knowledge it does not appear to be of universal occurrence, 
yet this arrangement of the spireme threads is so common and occurs 
in such widely separated groups as to indicate that it is of fundamental 
importance. Indeed, I suspect it will be found to be the most char- 
acteristic stage of the synaptic period. Montgomery (:00) seems to 
have been the first to call attention to the fact that in the growth period 
of the germ cells in many animals the spireme is in the form of loops 
with their open ends directed toward the distal pole, where they are 
more or less closely attached to the nuclear membrane. Such an 
arrangement of thé spireme during synapsis has since been described 
in a large number of forms. Among others in mammals by von Wini- 
warter (:00, :02); in amphibians by Kingsbury (’99, :02), Eisen (:00), 
Montgomery (:03, :04), Janssens (:05), Moore and Embleton (:06), 
and A. und K. E. Schreiner (:07); in fishes by Moore (’95), A. und 
K. E. Schreiner (:04, :05, :07), Maréchal (:04, :05), and by Farmer 
and Moore (:05); in insects by de Sinéty (:01), Baumgartner (:04), 
Montgomery (:05), Farmer and Moore (:05), Stevens (:05*, - :06*), 
Nowlin (:06) and Otte (:06); in arachnids by Montgomery (:05) and 
Wallace (05); in Peripatus by Montgomery (:00); in copepods by 
Lerat (:05); in gastropods by Meves (:02) and Bonnevie (:05, :06), 
and in annelids by A. und K. E. Schreiner (:06, :06*). In all cases 
where the number of loops has been determined there is always, 
as in the Orthoptera, at least during the latter part of the polar stage, 
one-half as many loops as somatic autosomes. ‘The above makes no 
pretence to being a complete list, but is given to show the wide occur- 
rence of the polar loops during synapsis. I have no doubt that a 
