1 88 Sargant. — Formation of the Sexual Nuclei 
within the pollen-tube ; a similar transverse fission of chromo- 
somes should occur. 
My observations on the oogenesis of Lilium Martagon 
give no support to this view. They confirm the conclusion 
of all previous observers in showing that the chromosomes 
of each generation are formed by longitudinal fission from 
the parent chromosomes. I have now concluded a corre- 
sponding set of observations on the spermatogenesis of the 
same plant. Here again we have a series of nuclear gene- 
rations to be examined so closely that, if a transverse fission 
of chromosomes should really take place in any one of them, 
the signs of it may not escape observation. 
So minute an inquiry into the details of karyokinesis as 
that required for this purpose cannot fail to furnish evidence 
on such general questions as the relation between nucleus 
and cytoplasm, the function of the nucleolus, and so forth. 
But one general result obtained from comparison of the 
spermatogenetic with the oogenetic series requires special 
mention. The first karyokinesis of either series differs in 
so many details from those which succeed it, that it may 
be said to present a different type of nuclear division. 
Professor Farmer has already pointed out the difference 
between the first and second nuclear divisions in the pollen- 
mother-cell of Lilium , applying to them the zoological terms 
heterotype and homotype 1 . How far this nomenclature is 
justified from a zoological standpoint, I am not competent 
to determine. But, using the words strictly in the sense 
suggested by their etymology, they seem to me peculiarly 
applicable to the case of Lilium Martagon. The second and 
third divisions of the micropylar nuclei in the embryo-sac 
of that plant follow the vegetative type of karyokinesis 
(I, p. 468). This is quite evident when Figs. 30 and 42 in 
Part I are compared with Fig. 6. The nuclear divisions 
1 J. B. Farmer, Ueber Kerntheilung in Lilium- An theren, &c., Flora, 1895, 
Heft 1. See also Farmer and Moore, On the essential Similarities existing 
between the heterotype nuclear Divisions in Animals and Plants, Anatomischer 
Anzeiger, xi, 1895, Heft 3. 
