302 J. 5. So MOORE: 
concludes with the following characteristic phrase :—‘‘ Durch 
die vorstehenden Erorterungen, glaube ich gezeigt zu haben 
dass zwar gewisse Vorginge bescrieben worden sind, die 
vielleicht mit der Chromosomenreduction in Zusammenhang 
stehen, dass uns aber eine wirkliche Einsicht in diesen 
Vorgang bisjetzt fehlt. Ks bleibt weitere Forschung vorbe- 
halten, dieses Dunkel aufzuhellen.” 
49. In 1893 I published! a preliminary account of some 
investigations concerning the course of the spermatogenesis of 
mammals, which I summarised in these words: “‘ There is in 
the Rat (i)? a period of indifferent cell formation, terminated 
by a mitosis with sixteen chromosomes, both in the primary 
and daughter-nuclei ; (ii) a period of growth (or rest) during 
which the sixteen chromosomes are converted into eight, and 
terminated by a division in which the daughter-nuclei 
spermatids still retain the number eight; (iii) a period in 
which the spermatids are converted into spermatozoa.” If 
a B y 
On ery tpl se cg, _—_ 
1(46) 1(8) 
itttese rector <a 
~~ 
Diagram III, showing course of Mammalian spermatogenesis. Reference 
letters same as in I. 
we now construct a diagram of the first and the second 
spermatogenetic periods in Mammalia (as in Diagram III), 
and place it side by side with that of the Elasmobranchs given 
' “ Mammalian Spermatogenesis,” ‘Anat. Anz.,’ Bd. viii, 1893, pp. 6883— 
688. 
2 Dr. Toyama, who apparently writes under the wing of Professor Ischi- 
kawa, speaks of my results respecting these phenomena in mammals as being 
“very improbable,” but as he produces no evidence relevant to the subject, I 
fail to see the force of such a criticism, and have therefore refrained from 
applying it to several portions of his own treatise, more especially as very 
little trouble with any native mammal would have enabled him to see whether 
the ‘ improbable” was true, 
