ASEXUAL REPRODUCTION 169 



nuclei, and endoplasm containing the green chromatophores ; c 4 , the 

 same at the commencement of germination. 



D 1 , early, and D 2 , later stages in the development of the gonads, the 

 spermary to the left, the ovary to the right ; D a , the fully-formed 

 spermary (spy) and ovary (ovy], each separated by a septum (sep) from 

 the filament. 



D 4 , the ovary after dehiscence, showing the ovum (ov), with small 

 detached portion of protoplasm ; D 5 , sperms ; D 6 , distal end of ripe 

 ovary, showing sperms (sp] passing through the aperture towards the 

 ovum (ov). 



D 7 , the gonads after fertilization, showing the oosperm (osp) still 

 inclosed in the ovary and the dehisced spermary. 



E 1 , oosperm about to germinate : E", further stage in germination. 



(c 1 and C 3 , after Strasburger ; c 2 and C 4 , after Sachs ; D and E, after 

 Pringsheim.) 



character of a membrane lining the cellulose coat. 

 Numerous small nuclei occur in the protoplasm, as well as 

 oil-globules (o), and small, close-set, ovoid chromatophores 

 (chr) coloured with chlorophyll and containing starch. 



Thus a Vaucheria-plant, like a Mucor-plant, is comparable 

 to a single multinucleate cell, extended in one dimension of 

 space so as to take on the form of a filament. 



Various modes of asexual reproduction occur in different 

 species of Vaucheria : of these we need only consider that 

 which obtains in V. sessilis. In this species the end of a 

 branch swells up (c 1 ) and becomes divided off by a septum 

 (sep), forming a sporangium (spg) in principle like that of 

 Mucor, but differing in shape. The protoplasm of the 

 sporangium does not divide, but separates itself from -the 

 wall, and takes on the form of a single naked ovoidal spore 

 (c 3 ), formed of a colourless cortical layer containing nume- 

 rous nuclei and giving off cilia arranged in pairs, and of an 

 inner or medullary substance containing numerous chroma- 

 tophores. 



The wall of the sporangium splits at its distal end (c 2 ), 

 and the contained spore (sp) escapes and swims freely in the 

 water for some time by the vibration of its cilia (c 3 ). After 



