THE CENTROSOME AND THE BLEPHAROPLAST 97 



apparatus as entirely independent of centrosomes, holding rather thai it 

 is produced by the differentiation of chondriosonies, and thai the resem- 

 blance of ciliated cells to spermatids, in which centrosomes do produce 

 the motor apparatus, is an accidental one. 



Conclusion. — In conclusion it may be said that it is highly probable 

 that cilia-bearing structures are not homologous in all plant and animal 

 groups. It is beyond question that in animals the centrosomes of the 

 spermatid produce the motor apparatus of the spermatozoon. That a 

 similar interpretation is to be placed upon the blepharoplasts in the sper- 

 matids (androcytes) of bryophytes, pteridophytes, and gymnosperma 

 appears to be equally well demonstrated. The blepharoplasts of the 

 flagellates are also probably centrosomic in nature, at least in certain 

 cases. In the " plasmodermal blepharoplasts" of motile alga cells we 

 have organs which, in the light of our present knowledge, do not appear 

 to belong to the centrosomic category, but final disposition of them musl 

 await further information concerning those alga* which possess both cen- 

 trosomes and blepharoplasts. It can scarcely be doubted that the basal 

 corpuscles of ciliated cells represent organs belonging to various categori 

 It must be left for further research to determine just how far thi 

 structures, which are functionally analogous, are homologous witli each 

 other and with other cell organs. 



Bibliography 5 



C< ntrosome and Blepharoplast 



Allen, C. E. 1912. Cell structure, growth and division in the antheridia of /'<</.v- 



irichum juniperinum WiLld. Arch. Zellforsch. 8: 121-188. pis. 6-9. 

 1917. The spermatogenesis of Polijtrichum juniperinum. Ann. Bot. 31: 269 292. 



pis. 15, 16. 

 Allen, R. F. 1911. Studies in spermatogenesis and apogamy in ferns. Trans. \\ 



Acad. Sci. 17 : 1-56. pis. 1-6. 

 Belajeff, W. 1888. Ueber Bau and Entwicklung der Spermatozoiden der ( iefass- 



kryptogamen. Ber. Deu. Bot. Gesell. 7: 122-125. 

 1894. Ueber Bau und Entwicklung der Spermatozoiden der Pflanzen. Flora 79: 



Erganzb.: 1-48. pi. 1. 

 1897a. Ueber den Nebenkern in spermatogencn Zellen und die Spermatogem Be 



bei den Farnkniutern. Ber. Deu. Bot. Ges. 15: 337 -339. 

 18976. Ueber die Spermatogenese bei den Schachtelhalmen. Ibid. 15. 339 342. 

 1897c. Ueber die Aehnlichkeit einiger Erscheinungcn in der Spermatogenese bei 



Thieren und Pflanzen. Ibid. 15: 342- 345. 



1898. Ueber die Cilienbildner in spermatogenen Zellen. Ibid. 16:140 144. pi. 7. 



1899. Ueber die Centrosome in den spermatogenen Zellen. Ibid. 17: 199 206. 

 pi. 15. 



van Beneden, E. 1876. Recherches sur lea Dicyemides, Burvivanta actuellea d'un 

 embranchement des Mesozo.-ihvs. Bull. Acad. Roy. Belg. 41: 1160 1205; 42: 

 35-97. pis. :;. 

 1883. Recherches sur la maturation <!«■ I'oeuf, la fecondation «-t In division cellu- 

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 7 



