OF THE PHYTOZOA. 



afterwards be again filled with water, motile Stej>hanos^hcerce reappear, from 

 which it seems probable that the green globes are the resting-spores of the 

 plant." These, it may be added, are with difficulty, if at all, distinguishable 

 from those of Chlamydococcus pluviaVis : they vary very much in size, and 

 apparently grow after entering on the state of rest. Their coloiu' is deep 

 green (occasionally yellowish or ohve) ; and they have a nucleus, and fre- 

 quently a nucleolus. We cannot do better than copy Mr. Currey's abridged 

 translation, in endeavouiing to convey the results arrived at by Cohn and 

 Wichura : — 



'' When the water is permitted to evaporate graxlually, the resting- cells 

 become yellow, and afterwards orange or red, and their contents have a more 

 oily appearance. The authors found that if the water was not permitted to 

 evaporate, the resting-spores, although continuing to live, did not become 

 developed into Steijlianosphcerce ; but when fresh water was poiu-ed upon de- 

 siccated resting-spores, twenty-four hours sufficed for the production of motile 

 Steplia nosjyhcf^i'ce. 



''The following is the process of transformation from the state of rest into 

 'the motile form. 



" The dried resting-spores take up the water, and their contents (hitherto 

 somewhat misshapen) gradually fill up the cavity of the containing mem- 

 brane, and become cloudy and granular ; the border becomes yellowish, and 

 the red coloimng matter is concentrated in the centre. The cells then begin 

 to divide ; and the successive forms assumed in this process will be better 

 imderstood by reference to XIX. 44-47, than by description. In pass- 

 ing from the state shown in fig. 45 to that shown in fig. 46, the outer mem- 

 brane has gradually become invisible. Up to fig. 47 the process has occupied 

 about two hoiu-s. The four daughter-ceUs (fig. 47) begin to quiver, and to 

 endeavour to separate from one another. Two cilia are now perceptible at 

 the pointed extremity of each of the four ceUs, by the action of which the 

 group begins to move as a whole, and in a laboui'ed manner, in the water ; 

 ultimately, however, all trace of the enveloping membrane and of the gluti- 

 nous connecting substance disappears, and one by one the daughter- ceUs 

 escape and become free. Pigs. 48 and 49 exhibit different forms of these 

 free daughter-cells, which contain two, three, or several granules (amylon ?) 

 and sometimes also vacuoles. The sharp end is often prolonged into a coloui^- 

 less beak. At this period there is no proper cellulose membrane. At the 

 moment of escaping, their diameter never exceeds O'OIO mm. ; but they soon 

 enlarge and attain a diameter of 0-013 to 0-015 mm. 



" Their form and the length of the beak are variable, the latter being some- 

 times altogether wanting. In form and motion they resemble exactly the naked 

 primordial-cells, which are produced by division from the resting-cells of 

 Chlamydococcus lyiuvicdis. The authors have never seen the resting-cells of 

 SteplianospJiceroi di\ide into more than four parts, but think it not improbable 

 that division into a greater number (eight or possibly sixteen) sometimes 



OCCUl'S. 



'' The length of time which elapsed between the immersion of the diied 

 resting-spores and the fii^st appearance of the motile ceUs varied from nine to 

 twenty-four houi^s. It was noticed that those resting-spores which did not 

 produce zoospores within six days never did so afterwards, although they 

 continued to live and were perfectly healthy. 



'' Zoospores, produced in the month of November, did not advance beyond 

 the fii'st stage (fig. 49). Others, however, produced in March, remained only 

 a few houi\s in that condition, after which time a delicate membrane was 

 formed round the body of the piimordial cell (XIX. 50 ); this membrane was 



