CHROMOSOME* NUMBER AND PAIRS IN AMBYSTOMA 209 
exists in pairs in the germinal line is evidenced by their behavior 
during the maturation period. 
Montgomery (’01) presented evidence for the recognition of 
pairs in the spermatogonia, basing his argument upon the signifi¬ 
cance of the chromosome number in Euschistus. Sutton (’02) 
showed by means of a comparison of many camera-lucida draw¬ 
ings of spermatogonial complexes of Brachystola magna that 
these chromosomes form a duplicate series of lengths, and by 
means of measurements with a pair of dividers that the chro¬ 
mosomes of the early primary spermatocyte prophases are graded 
into the same series of relative sizes. Meves (’ll) interpreted 
his measurements upon spermatogonia of Salamandra maculosa 
as failing to demonstrate pairs. Meek (’12) has made linear 
measurements upon the spermatogonia and secondary spermat¬ 
ocytes of a number of animals, interpreting his results as con¬ 
firming the claim of the existence of pairs. Robertson (’15, ’16) 
also supports this view with metrical data in certain Orthoptera, 
and Hance (’17 b; ’18 a) confirmatively interprets his measure¬ 
ments in the germinal and somatic cells of Oenothera and the 
pig. In unmeasured spermatogonial chromosomes of the Dip- 
tera, Stevens (’08, ’10, ’ll), Metz (’14, ’16), and Whiting (’17) 
show very convincing evidence of pairs for the homologues are 
associated side by side. Wilson’s (’06, p. 11) figures of Anasa 
and Hoy’s (’16, p. 336; ’18) figures of Anasa, Epilachna, and 
Diabrotica also support this conclusion. The majority of other 
authors as a result of their general observations have expressed 
the belief that the chromosomes exist as a duplicate series. 
Furthermore, the existence of pairs in the spermatogonia is 
practically proved by parasynapsis where the chromosomes of 
the last spermatogonial division unite side by side and remain 
so until separated by the reduction division. This statement is 
made possible by Wenrich (’16) who, besides confirming the 
already numerous and all but conclusive evidences of parasynapsis 
by Janssen (’05, ’09), A. and K. E. Schreiner (’06, a and b; 
’08, a and b), Wilson (’12), and many others, carries the demon¬ 
stration a step further by actually tracing a well-marked chro¬ 
mosome pair A (p. 76) continuously through every stage of 
