Dixon — First Mitosis of Spore-mother-cells of Lilium. 11 



original dolichonematous thread. "Whether or no, a differential division 

 is secured by the succeeding mitosis of the daughter nuclei is a matter 

 of dispute. Belajeff, ^ Guignard, ^ and Gregoire, ^ all maintain that 

 no true longitudinal fission of the chromosomes takes places in that 

 mitosis. Consequently, if we accept the scheme put forward in this 

 note, a reducing division does take place in the formation of the sexual 

 cells. This position is accepted by Belajeff, who believes that there is 

 but one longitudinal fission in the first mitosis. Guignard and Gregoire 

 urge that although there is no longitudinal fission in the second 

 mitosis, that there is a double fission in the first, which compensates 

 for the want of one in the second. The chromosomes which have 

 arisen by the second longitudinal fission of the first mitosis come to lie 

 and to end, and in the second mitosis separate by transverse fission. 



General agreement on this difficult point, as to whether there is 

 an actual longitudinal fission in the second mitosis or not, is far from 

 being attained. Thus Miss Sargant, Strasburger* and Mottier, and 

 myself, have convinced ourselves that at least all the appearances of 

 longitudinal cleavage are presented in this second mitosis. If this view 

 is accepted the scheme advocated here involves no reducing division. 



In conclusion, I wish to express my thanks to Mr. Charles Green, 

 who kindly drew several of the diagrams used in this note, and helped 

 me in the construction of several of the remainder. 



^TJeber die Eeductionstheilung des Pflanzenkernes. Eer. d. deutsch. hot. Ges., 

 1898. 



"^ Loc. cit. ^ Loc. cit. 



^ Note Added in the Press. — Still more recently Strasburger has returned 

 again to the ■view that no longitudinal cleavage takes place in this second mitosis. 

 Ueher Reductionstheilung, &c., in Pflanzenreicb. Jena, 1900. 



