574 AMERICAN NATURALIST. [Vol. XXXVIIl. 



that these structures are permanent in the cell. After nuclear 

 multiplication is ended segmentation proceeds until the nucleate 

 masses of protoplasm separate from one another as zoospores. 

 Then a body may be found lying in contact with the plasma 

 membrane and bearing a pair of cilia (Fig. <)b). This basal body 

 (blepharoplast) by its reaction to stains seems to be entirely 

 distinct from the plasma membrane and is connected with the 

 nucleus by very delicate threads. There is a time just previous 

 to the differentiation of the zoospores when "the nuclei lie very 

 close to the cleavage furrow that finally separates the adjacent 

 zoospore origins. A granule may sometimes be observed close 

 to these nuclei and it is possible that this is the first appear- 

 ance of the basal body (blepharoplast). If this should prove 

 correct the structure may have a direct relation to the kinoplasm 

 around the nucleus, a relation that is afterwards maintained 

 through the two or three delicate fibers that connect these 

 structures. Thus the blepharoplast if not directly derived from 

 a centrosome may at least have its origin from the same region 

 of kinoplasm. However these possibilities are mere speculations 

 and the investigation of these points is very much to be desired 

 in a number of algal and fungal types. 



We are now brought to the views of Strasburger as expressed 

 m his writings of '92 and : 00. His investigations have been 

 chiefly on Vaucheria, Cladophora and CEdogonium. In all of 

 these forms the cilia come from a body (blepharoplast) which 

 he believes to arise from the outer plasma membrane (Haut- 

 schicht). The nucleus lies close to the plasma membrane at the 

 time when the blepharoplast is formed and may determine its 

 development there as a dynamic center, but the blepharoplast is 

 not a centrosome according to Strasburger. It is of course 

 lasma membrane and 



^ - a cilia forming organ. 



The blepharoplast is extraordinarily large in CEdogonium (see 

 l^ig. 9 and develops a ting of 



wmie at the same time fibrillar rays grow back into the cyto- 

 plasm and probably help to give a compact organization to the 

 zoospore. This structure is very suggestive of the centrosphere 

 and aster that cuts out the ascospore (see Section II, Free Cell 



