300 J; i. 8+ MDORE; 
sion. The divisions which result in the formation of the polar 
bodies perform the function of the Reductionstheilung as re- 
gards the ovum, and the final divisions of the sperm mother- 
cells have this function in the case of the spermatozoa. In 
both cases the Reductionstheilung does not consist in the 
idants (chromosomes) becoming split longitudinally, and in 
their resulting halves being distributed equally amongst the 
two daughter-nuclei, as in ordinary nuclear division, but in one 
half of the entire number of rods passing into one daughter- 
nucleus, and the other half into the other.” 
46. The absence in the spermatogenesis of Elasmobranchs of 
any Reductionstheilung is thus of peculiar interest, because the 
fundamental way in which Weismann has used this conception 
of a Reductionstheilung as a basis on which to build up his 
supposed explanation of heredity, renders it evident that any 
widespread collapse in the alleged universal existence of this 
process, either among animals or plants, will in the long run 
bring down the whole speculative superstructure with it. 
47. Now with respect to plants, the two highest living 
authorities, Strasburger! and Guignard,? have already dissented 
from Weismann’s views; and the former, in his address to the 
Biological Section of the British Association meeting at Oxford 
last year, expressed his opinion of the Reductionstheilung as 
follows :—‘‘ There is no such thing among plants as nuclear 
division resulting in the reduction of one-half of the chromo- 
somes. Such a conception involves the assumption that the 
entire, not longitudinally-split, chromosomes of the mother- 
nucleus become separated into two groups, each of which 
goes to form a daughter-nucleus.” So we may take it that the 
Weismannistic conception of the “ Reductionstheilung,” “so 
far as is known in plants,” fails. 
48. With respect to animals, Boveri,’ in his “ Befructung,” as 
far back as 1890, after postulating the chromatin as the 
1 © Ans. Bot.,’ vol. vili, 1894. 
2 « Anns. d. Sc. Nat.,’ Bot., 1891. 
3 «Hrgebnisse der Anat. und Entwicklungsgeschichte,”’ Bd. i, 1891, 
pp. 458, 459. 
