156 THE PHENOMENON OF 



compresses the contents within continually narrower 

 boundaries, more and more excludes intercourse with the 

 external world, and puts a term to growth. Thus the 

 life of the plant builds its tomb in the very cell — dies 

 away at last in its own work. 



That the origin of the cell precedes its enclosure by 

 a cell-membrane, is shown most distinctly in those cases 

 in which the cell originates free, that is, without contact 

 with the mother-cell, or where it becomes free by being 

 expelled immediately after its production. The last 

 condition occurs in the swarm-cells, or active gonidia of 

 the Algae, which so long as the motion lasts, possess no 

 cell-membrane separable from the contents, and must 

 be regarded as bounded merely by the primordial utricle, 

 which is intimately connected with the contents. It is 

 well known that by the action of dilute acids or spirits of 

 wine, the contents of the cell are contracted and wholly 

 or partially removed from the cell-membrane, which thus 

 appears as a structure clearly separated from the contents. 

 The active gonidia of (Edogonimn, IBulbochcBte, TJlotJirix, 

 Draparnaldia, Stigeodonium, Chcetophora, Hydrodictyon, 

 and other genera which I have repeatedly examined in 

 reference to this point, contract, when so treated, entirely, 

 without leaving a colourless membrane at the boundary 

 of the original dimensions, which does always occur after 

 germination has commenced. Thus the gonidia of 

 TJlothrix and Hydrodictyon exhibited a hyaline vesicle, 

 the contents of which were contracted on the application 

 of tincture of iodine, a few hours after they had come 

 to rest, on the same day that they were born. That 

 these gonidia possess another membrane, intimately con- 

 nected with the contents (the primordial utricle), is 

 testified by their smooth and exact outline, and further 

 by the phenomena which present themselves in the 

 solution frequently taking place soon after birth in weak 

 gonidia. In such cases the cell is seen to acquire a 

 globular form and swell up ; through absorption of water, 

 large hyaline cavities originate, displacing the contents. 



