212 



TTTE BOTANICAL MAGAZINE. 



[Tol. XXXV. Yo 419. 



Text-figs. 1-13 (X1120) Explanation in text. 



of the upper two cells contain large and small nuclei, while in the 

 lower two, each possesses a single large one. On the other hand, 

 one or two large nuclei are often found in each divided cell as re- 

 presented in Text-fig. 10—13. Judging from all the features shown in 

 these figures it seems most probable that the nucleus of the fertilised 

 carpogonium detaches a small nucleus during the eary period of 

 carpospore-formation, or the nucleus of zygote may divide into two 

 halves of equal size, one of which destined to degenerate, gradually 

 assumes a small size as in the case of the zygotes of Zygophyceas 

 or the gametes of certain diatoms. In any case the small nucleus 

 disintegrates sooner or later, but often persists and divides once or 

 twice before going to degeneration. 



The nuclear phenomena described above may justify the conclusion 

 that the fertilised nucleus in the carpogonium throws out a part of 

 the nuclear substance ; this may be regarded as a primitive form of 

 the reduction division. The recent investigations on the lower members 

 of Nemalionales, as Batrachospermum (5 e), Nemalion (2), Scinaia 

 (lib), which do not produce tetraspore, agree in the inference that 

 the reduction division takes place in the first division of the fertilized 

 nucleus and therefore the cystocarp is gametophytic in character. So 

 in Bangiales, in which the fertilised carpogonium directly becomes 

 carpospores, it is reasonable, as far as w^e know, to assume that the 

 reduction division occurs in the zygote directly after the fertilisation 

 as in the case of Chloroi^hyceae, Conjugatae, Characese etc. And it 

 is highly probable that in Porphyra whose nuclear phenomena are 



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