ALG^. lOl 



repetition of the perfect plant, requirin<:j only extension 

 of parts to assume completely its size and aspect. This 

 answers to the first part of the definition of a crypto- 

 gam ; but the plant does not germinate, he can dis- 

 cover no sexual indications, though germination does 

 not take place by the protrusion of a filament, and the 

 protoplasm of the cell at once gives rise to a new 

 plant. He believes it to belong to the vegetable 

 kingdom, and he feels that he has hit upon one of 

 those exceptional cases which defy mathematical accu- 

 racy. But still he has no doubt about the matter. 

 The plant is Nostoc comimine (Fig. i8), a widely dis- 



FiG. 1 8. — Xosioc commune. 



tributed alga, bordering very close upon the gelatinous 

 lichens." ^ 



There are several species, but this is the commonest, 

 and on some accounts the most interesting, especially 

 in its habitat and in the manner of its appearance. 

 Curious notions have been current as to its origin, 

 since some have supposed it to fall from the clouds in 

 a shower of rain, which may have originated in its 



* Berkeley, "Introduction to Cryptogamic Botany," p. 16. 



