ARCHER, OX DESMIDIACILaS. 233 



Now I regret I am unable to affirm that the numer- 

 ous orbicular, spore-like bodies in the neighbourhood 

 (Fig. 5) are the produce of the contents of the organism 

 in question, as I did not see their formation — but I 

 cannot doubt it. When I made this particular gather- 

 ing, I did not meet the Closterium so affected in numbers 

 sufficient to make any definite observations ; but I suppose 

 the plants must have given birth to and emitted their con- 

 tents in the form of the gonidia lying about. For, certainly, 

 the bodies scattered around did not occur anywhere else, but 

 always in the neighbourhood of a Closterium containing these 

 organisms ; and where they nearly all, or a few only, still 

 contained their endochrome, these abounded close by in the 

 relative numbers to be expected. Admitting them to be 

 such, it may appear questionable whether this growth be 

 connected with the development of the Closterium itself, or 

 whether it be a true parasite. I am disposed myself to think 

 the latter. But, be this as it may, I need hardly insist on 

 the essential distinctness between the phenomenon depicted 

 in Fig. 5, and the condition of Docidium shown in Figs. 1 to 4. 

 It may be well to say that the three ovate ciliated bodies on 

 the Plate near Fig. 4 represent the zoospores appertaining 

 to it, whereas all the other scattered orbicular bodies be- 

 long to Fig. 5. Notwithstanding any description I can 

 offer is so very incomplete, I venture to think the draw- 

 ing itself (a faithful copy from nature) may prove interestin°\ 

 It seems highly probable that Ehrenberg's genus Polysolenia, 

 included by him and by Kiitzing in Desmidiacae [vide Kutzing, 

 " Species Algarum ") must have been truly a Closterium 

 (probably C. didymotocum) so attacked. I draw attention 

 here to this very interesting growth, in order to guard against 

 any possibility of its being thought the remarkable condition 

 of Docidium is identical with it, or that I may have myself 

 in any way mistaken the one for the other. 



Here, however, my observations conclude, for I am totally 

 unaware of the after development of the motile gonidia, the 

 original formation and emission of which I have described. 

 It may be urged that I cannot prove these bodies to be truly 

 zoospores, because I cannot prove they grow into young 

 Docidia, as can more or less readily be done according to the 

 species in various other Algas, in which the growth of the 

 zoospores into young plants similar to the parent is witnessed 

 with not great difficulty. Possibly the bodies I have described 

 may be but equivalent to those described in somealgse asmicro- 

 gomdia by the German writers ; but I cannot for the present see 

 the probability of this assumption, and imagine they are more 

 likely to be true motile buds, i. e. zoospores. It will be borne 



