266 



REDUCTION OF THE CHROMOSOMES 



essentially in agreement with the facts described in Ascaris, and 

 involves no reduction-division. I^ssentially the same result is reached 

 by Guignard ('98) in his latest paper on Naias, and by Gregoire ('99) 

 in the Liliaceae. 



Strasburger twice shifted ground in rapid succession. First ('97, 2), 

 with Mottier ('97, i), he somewhat doubtfully adopted a view agreeing 



r^- 



.^09 





\vVfe!iiIli! 



E 





Fig. 133. — The first maturation-division in flowering plants. [F, STRASBURGER and Mot- 

 tier ; the others from MoTTIER.] 



A. Mother-cell of the embryo-sac in LUium ; early prophase of first division ; chromatin- 

 threads already longitudinally divided. D. Slightly later stage (split spireme) in the nucleus of 

 the pollen-mother-cell. C. A slightly later prophase (pollen-mother-celi, Podophyllum^ with 

 twisted split spireme. D. Earlier prophase (Lilium, female) ; split twisted chromosomes. E. 

 Equatorial plate (Liliniii, male). F. First maturation-spindle (Fritillaria, male). G. Diver- 

 gence of the daughter-chromosomes {Liliidii, male). 



essentially with the interpretation of Vom Rath, Riickert, etc. (p. 247). 

 The primary rods split once, and bend into a V, the branches of 

 which often come close together, and may be twisted on themselves, 

 thus giving the appearance of the second longitudinal split described 

 in Strasburger's paper of 1895. The two halves of the split U then 

 separate, opening out from the apex, to form the o -figure. In the 



