LESS, xvi ASEXUAL REPRODUCTION 171 



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

 same at the commencement of germination. 



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

 spermary to the left, the ovary to the right ; D 3 , 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 2 , further stage in germination. 



(C 1 and c :} , 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 (0), 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 



