58 PRINGSHEIM, ON THE 



granular plasma wliicli it contains, as has been often 

 observed in other vegetable cells, is attached to the walls, 

 •Avhilst the iiuid portions of the contents are collected in the 

 centre. The amylon-eell of which I have just spoken is 

 embedded in the granular parietal layer. Ordinarily, no 

 other kind of development takes place until the zoospore has 

 attained a diameter of ^,^ m.m. But, if during its vegetation 

 it has undergone alternations of dryness and moisture, it in- 

 creases still more without modifying its earliest form, and its 

 diameter may measure -^'jj m.m., or even -^ m.m., whilst 

 its cellulose envelope becomes gradually thicker, and the 

 nucleus from which the chlorophyll has entirely disappeared 

 assumes more or less of a broAvn tinge. 



These differences in the globular zoospores do not, how- 

 ever, influence their ultimate development. In all, the endo- 

 chrome divides successively into different portions, then the 

 external layers of the membrane soon give way, and afford a 

 free passage to the internal layers which are extruded in the 

 form of a gelatinous herniary sac. Into this sac the plastic 

 masses now become separate and distinct from the breaking 

 up of the primitive endochrome, enter, and present the regular 

 form (fig. 8), and all the characters of true zoospores. These 

 new bodies are of considerable size ; they differ from the ordi- 

 nary and well-known zoospores oi Hydrodictyon,QXidi bear more 

 resemblance to those of (Edogonium, but instead of showing, 

 as the latter do, a circle of vibratile cilia, they only possess 

 one or two at their anterior and semi-transparent extremity. 

 The numljcr and size of the fresh zoospores which are thus 

 produced within the primitive ones, vary according to the 

 dimensions of the latter, and the division of their nucleus 

 into more or less numerous portions. According to my own 

 observations, from two to five new zoospores replace the old 

 ones; the size even of those issuing from the same matrix varies 

 considerably, for example, between -^ m.m. and -j^-^ m.m. 

 in length, and between ^^ m.m. and V- m.m. in thickness. 

 The herniary sac of which we have spoken above, is easily 

 ruptured (fig. 9), and allows the new zoospoi-es to escape in 

 a state of as gi'eat activity the moment they are liberated, as 

 if they were legitimate zoospores ; but after some minutes, 

 frequently within the generative utricle itself (figs. 10 and 11), 

 they become motionless, and assume the shape of almost poly- 

 hedral cells, whose angles are produced like horns or long ap- 

 pendages (fig. 12). 



These angular cells, or polyhedrons, as they may be called, 

 are highly polymorphous ; they groAv, and the appendages are 

 multiplied at various points on their surface (figs. 13 — 17). 



