KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 203 
threads, arising by longitudinal division, but remaining con- 
nected at their ends, and already clearly formed at an earlier 
stage. Compare with this van Beneden’s statement (ante). 
When now transverse division takes place at the equator there 
is no difference from Flemming’s principle of karyokinesis ; and 
the longitudinal splitting described by Carnoy may take place in 
the Dyaster stage without prejudice to this principle, as van 
Beneden and Flemming show.- This, therefore, is not the pri- 
mary process, so significant for karyokinesis, but another and a 
secondary one, which perhaps has no general significance, since 
it has hitherto been observed only in a few cells (sexual cells). 
(Compare Weismann, ‘ Directive Corpuscles,’ p. 39, et seq.) 
In another deviation, which Flemming describes as the 
“homootypic Form” (that is to say, ‘‘a form more 
like the usual one than the oné just described, which he names 
‘heterotypic’”), it would appear as if Carnoy were correct 
in hisassertion, that longitudinal splitting may be entirely absent. 
Even here, however, longitudinal splitting occurs in the spirem 
stage ; the sister-threads quickly separate completely from one 
another, become short and thick, so that they resemble the 
primary threads (chromosomes), and might easily be mistaken 
for them. In this case no regular monaster is formed at the 
equator, but simultaneously with their formation some of the 
threads move towards the poles. The commencement of 
metakinesis coincides with the monaster form. Now, here in 
the formation of the daughter-nuclei, if one had not noticed 
the longitudinal splitting in the spirem stage, one might well 
suppose that a karyokinesis occurred without longitudinal 
splitting. Flemming is certainly right when he suggests, with 
that calmness and objectivity usual with him—which distin- 
guishes all his works so favorably—that Carnoy has overlooked 
in his abnormal discovery the first longitudinal splitting. 
On the other hand, one cannot blame Carnoy if he does not 
admit this without more ado, but protests with vehemence, and 
claims that anyone who wishes to confute him must investigate 
the same objects which he did. Till this happens the dis- 
pute will not be ended. Indeed, I ought to add that suitable 
