M ur <| uetto, Manifestation« of polarity in plant cells wbich usw. 283 



pollen-mother-cells of Larix 1 ) it is to b< j nuted that a large nuinber 

 of them come no nearer to presenting a developmental history of 

 the spindle figure carefully worked out on technically adequate 

 preparations than did the earlier centrosome studies on plant cells. 



There have also appeared since the „Bonner Studien 1 ' a 

 large nuniber of päpers in which granules or aggregations of 

 granules are described as lying at tlie spindle poles in various 

 species of higher plants and considered as of the nature of centro- 

 somes. 2 ) The same criticism applies to all of these latter investi- 

 gations — the content themselves too much with the Unding of 

 a granule or granules at the spindle poles during one or several 

 stages of mitosis without tracing the development of these granules 

 and their relation to the formation of the spindle. That however 

 the mere occasional finding of a granule at the poles of the com- 

 pleted spindle or in any other isolated stage of mitosis shows 

 nothing as to the function or nature of that granule has been 

 repeatedly shown. 



From the Standpoint of our knowledge of the so-called blepharo- 

 plast, the question of the existence of central bodies in the higher 

 plants assumes a somewhat different aspect. It has been shown 

 by Belajeff, 3 ) Shaw, 4 ) and others that blepharoplasts occur quite 

 generally among the vascular cryptogams, and the work of Hirase, 5 ) 

 Ikeno, 6 ) and Webber 7 ) has given us füll data as to their presence 

 and structure in the lower Gymnosperms. They appear as well 

 defined organs of the cell although present, as far as known, 

 during but a limited number of cell generations. In their function 

 as ciliaforming organs, the blepharoplasts show a behavior ana- 

 logous to that of the central bodies of animal cells during the 



x ) Allen, 0. E.: The early stages of spindle-forniation in the pollen- 

 mother-celle of Larix. (Ann. Bot. Yol. XVII. 1903. p. 281.) 



3 ) See for instance Bernard, Quelques remarques a propos des centres 

 kinetiques. (Jour. de Bot. XIX. 1905. p. 80.) who also gives an extensive list 

 ■of works belonging in this category. 



3 ) Belajeff, W. : Über den Nebenkern in sperrnatogenen Zellen und die 

 Spermatogenese bei den Farnkräutern. (Ber. d. Deut. bot. Ges. Bd. XV. 

 p. 337.) Über die Spermatogenese bei den Schachtelhalmen. (Ibid. Bd. XVII. 

 p. 399.) Über die Ähnlichkeit einiger Erscheinungen in der Spermatogenese 

 bei Tieren und Pflanzen. (Ibid. p. 342.) Über die Cilienbildner in den sper- 

 rnatogenen Zellen. (Ibid... Bd. XVIII. p. 140.) 



4 ) Shaw, W. R. : Über die Blepharoplasten bei Onoclea und Marsilia. 

 (Ber. d. Deut. bot. Ges. Bd. XVI. 1898. p. 177.) 



5 ) Hirase, S.: Notes on the attraction-spheres in the pollen-cells of 

 Ginkgo biloba. (Bot. Mag. Tokyo. Vol. VIII. 1894. p. 359); Etudes sur la 

 fecundation et l'embryogenie du Ginkgo biloba. Jour. Coli. Sei. Imp. Univ. 

 Tokyo. Vol. VIII. Pt. IL 1895. p. 307); Etudes sur la fecondation et l'embrvo- 

 genie du Ginkgo biloba. (Ibid. Vol. XII. Pt. II. 1898. p. 103.) 



6 ) Ikeno, S.: Zur Kenntnis des sogenannten ,.centrosomähnlichen'' Körpers 

 im Pollenschlauch der Cycadeen. (Flora. Bd. 85. 1898. p. 15.) Untersuchungen 

 über die Entwicklung der Geschlechtsorgane und den Vorgang der Befruchtung 

 bei Cycas revoluta. (Jahrb. f. wiss. Bot. Bd. 32. 1898. p. 557.) Also Jour. Coli. 

 Sei. Imp. Univ. Tokyo Vol. XII p. 152. 



"') Webber, H. J.: Peculiar struetures oecuring in the pollen tube of 

 Zamia. (Bot. Gaz. Vol. XXIII. 1897. p. 453.) Spermatogenesis and fecundation 

 of Zamia. (Bur. Plant Ind. Bull. No. 2. 1901. U. S. Dept, Agri.) 



