5 1 8 Farmer. — On Spore- Formation and 
of the Lily a true homotype mitosis occurs, and that it in every 
way resembles those mitoses in the vegetative cells of the 
plant, except in so far as the retention of the reduced number 
of chromosomes is concerned. I have observed the chromo- 
somes lying in pairs, and arrayed on the spindle in such 
a way as hardly to admit of a doubt as to their having arisen 
by a longitudinal fission, exactly like that in the chromosomes 
of the endosperm nuclei, for example. 
But it would appear that not all Phanerogams exhibit the 
difference between the two mitoses which is so pronounced in 
the Lilies. Thus Strasburger 1 states that in Orchis mascula 
the chromosomes of the two successive mitoses in the pollen- 
mother-cells are quite similar in appearance. Here, then, it 
seems that, as in liverworts and in some animals 2 * * , the two 
mitoses are both similar, and approximate to the heterotype 
form. 
A study of these divisions affords not the slightest evidence 
in favour of any reduction-division (in Weisman’s sense) taking 
place. The only point at which, so far as I can see, it might 
conceivably occur, is in the period of rest which intervenes 
between the last archesporial division and the first spore- 
mother-cell mitosis, in which the reduced number of chromo- 
somes is already complete. It might be suggested that the 
chromosomes of the last archesporial mitosis had come together 
laterally and in pairs, so that what has been here and by other 
writers described as a longitudinal fission in the chromosome 
really represents the partial lateral fusion, or perhaps re-separa- 
tion of a pair of entire ones. The apparent division in this 
case would then really amount only to a sorting out of the 
two members of each pair, a process which would certainly 
fulfil the requirements of the ‘ Reductionstheilung 5 if it could 
be proved to take place. But the great similarity of the first 
heterotype in plants with the first heterotype division in 
1 Karyokinetische Probleme. Pringsh. Jahrb., Vol. xxviii, p. 192. 
2 Moore, On the Germinal Blastema and the nature of the so-called ‘ Reduction- 
division ’ in the Cartilaginous Fishes. Anat. Anz., Bd. IX ; also, On the Maturation 
of the reproductive elements in Elasmobranchs. Quart. Journ. of Micr. Sc., 1895. 
