"2S4: Marquette, Manifestations of polarity in plant cells which usw. 



metamorphosis of the spermatid. Whether they also play a role 

 analogous to that of the central bodies during nuclear division is 

 perhaps still an open question. Webber concluded 1 ) that the 

 blepharoplast takes no part in nnclear division and that it is not 

 the honiologue of the centrosome. a conclusion which Strasburger 2 ) 

 also reached after reviewing the evidence at band at the time. 

 Hirase 3 ) and Ikeno 4 ) on the other hand considered the blepharo- 

 plast the homologue of the centrosome although they present no 

 very convincing evidence of its participation in nuclear division. 

 On the other hand, Belajeff 5 ) in his observations on the micro- 

 gametophytes of Marsilia traces the blepharoplast through a number 

 of cell generations preceding the antherozoids and finds that they 

 divide preparatory to nuclear division and that the spindle figure 

 develops about the separating halves just as about the central 

 bodies in aninial cells. This account of Belajeff's is the most 

 complete we have describing a participation of the blepharoplast 

 in nuclear division. It is to be hoped that further investigation 

 will throw more light on the origin of the blepharoplast and its 

 possible relations to the spindle. both in the vascular cryptogams 

 and in the Cycads. 



YThile the multipolar stage in spindle development has been 

 found to be of wide spread occuiTence it appears that its multi- 

 polar polyarch origin. to employ Strasburger's termfnology, is 

 restricted in general to sporogenous tissues; that in vegetative 

 cells the spindle is diarch froni the beginning. Eosen 6 ) gave an 

 essentially correct sketch of spindle development in vegatative 

 cells, but it is especially due to Nemec's work 7 ) that attention 

 has been called to the drfferences between the mitoses in vegetative 

 and in sporogenous tissues. Strasburger 8 ) has however pointed 

 out a series of intermediate types which indicate that there is no 

 such great disparity in the methods of spindle formation in sporo- 

 genous and vegetative tissues as Xemec at first maintained. 



As far as the central bodies are concemed they are no more 

 in evidence in those cells in which the spindle is diarch from the 

 beginning of its appearance than in the sporogenous cells where 

 the spindle has a polyarch origin. so that at present the view is 



x ) Webber, H. J.: Xotes on the fecundation of Zamia and the pollen- 

 tube apparatus of Ginkgo. (Bot. Gaz. Vol. XXIY. 1897. p. 232.) Spermatogenesis 

 and fecundation of Zamia. 1. c. p. 77. 



"-) Strasburger, E.: Hist. JBeitr. VI p. 185. 1900. 



3 ) Hirase: Jour. Coli. Sei. Imp. Univ. Vol. XU p. 103. 



4 ) Ikeno: Jahrb. f..wiss. Bot. Bd. 32 p. 571. 



5 i Belajeff, W.: Über die Centrosome in den spermatogenen Zellen. 

 (JBer. d. Deut. bot. Ges. Bd. XVHI. p, 199.) 



6 ) Rosen, F.: Beiträge zur Kenntnis der Pflanzenzellen. (Cohn : s Beitr. z. 

 Biol. d. Pflanzen. Bd. VII. 1895. p. 225.) 



7 ) Nemec, B.: Über die Ausbildung der achromatischen Kernteilungs- 

 figur im vegetativen und Fortpflanzungsgewebe der höheren Pflanzen. (Bot. 

 Ctblt. LXXIV. 1898. p. 1.) Zur Physiologie der Kern- und Zellteilung. (Bot. 

 Ctblt. LXXVII. 1899. p. 241.) Über die karYokinetische Kernteilung in der 

 Wurzelspitze von Allium cepa. (Jahrb. f. wiss."Bot. Bd. XXXIII. 1899. p. 313.) 



8) Strasburger, E.: Hist. Beitr. VI p. 118, 1900. 



