MICROSCOPIC FORMS OF VEGETABLE LIFE. 



253 



a firm cellulose envelope, and may remain for a considerable length of 

 time in a dormant condition, in which they are known as ' statospores;' 

 and that in this state they are able to endure being completely dried np 

 without the loss their vitality, provided that they are secluded from the 

 action of Light, which causes them to wither and die. In this state 

 they bear a strong resemblance to the cells of Protococcus. The first 

 change that manifests itself in them is a simple enlargement; next, the 

 endochrome divides itself successively into distinct masses, usually from 

 two to five in number; and these, when set free by the giving way of the 

 enveloping membrane, present the characters of ordinary 'zoospores,' 

 each of them possessing one or two flagella at its anterior semi-trans- 

 parent extremity. Their motile condition, however, does not last long, 



Etc. 149. 



FlO. 150. 



Development of Achlya prolifera : A, dilated 

 extremity of a filament b, separated from the 

 rest by a partition a, and containing gonidia in 

 progress of formation ; B, conceptacle discharg- 

 ing itself, and setting free gonidia, a b, c, f c, 

 portion of filament, showing the course of the 

 circulation of granular protoplasm. 



Process of cell-multiplication 

 in Conferva glomerata .'A, por- 

 tion of filament with incomplete 

 separation at a. and complete par- 

 tition at 6; B, the separation com- 

 pleted, a new cellulose partition 

 being formed at a ; c, formation 

 of additional layers of cellulose 

 wall c, beneath the mucous invest- 

 ment d, and around the ectoplasm 

 a, which incloses the endochrome 

 b. 



often giving place to the motionless stage before they have quite freed 

 themselves from the parent-cell; they then project long angular pro- 

 cesses, so as to assume the form of irregular polyhedra, at the same time 

 augmenting in size; and the endochrome contained within each of these 

 breaks-up into a multitude of gonidia, which are at first quite independ- 

 ent and move actively within the cell-cavity, but soon unite into a 

 network that becomes invested with a gelatinous envelope, and speedily 

 increases so much in size as to rupture the containing cell-wall, on 

 escaping from which it presents all the essential characters of a young 

 Hijdrodictyon. Thus, whilst this plant multiplies itself by ( macro- 

 gdnidia' during the period of its most active vegetation, this method of 

 multiplication by 'micro-gonidia' appears destined to secure its perpetu- 

 ation under conditions that would be fatal to it in its perfect form. 



