AECHEK ON STEPHANOSMJERA PLTJVIALIS (COHN). 157 



made themselves apparent, conspicuous even to the naked eye, by their 

 mass. I should be disposed to hold that here, as elsewhere, resemblance 

 may by no means necessarily demonstrate identity; and although these 

 isolated motile bodies, thus proceeding from Gonium and Stephano- 

 sphaera respectively, were so much alike as to be indistinguishable to the 

 eye, for the present I doubt not there must have been between them some 

 more subtle distinction, and that in the progress of development in their 

 natural conditions, they would each have gone into their respective ma- 

 ture forms (and this notwithstanding what I have afterwards to ad- 

 vance), although Cohn did not see (nor have I noticed) the isolated cells 

 of Gonium, but only those still undisturbedly in situ, become segmented, 

 and directly form a new young Gonium-tablet, whilst on the other 

 hand, as has been stated, it can be demonstrated by direct observation 

 that in Stepbanosphasra the single Chlamydomonas-like primordial cell 

 eventually produces a new Stephanosphaera-globe. Cohn neither in 

 his first, nor in his and Wichura's subsequent memoir on Stephano- 

 sphaera, makes any allusion to any development of Gonium making its 

 appearance in the material which formed the subject of his earlier ob- 

 servations on the former organism ; but I find that he incidentally 

 mentions, in his memoir on Gonium* that on one occasion at least a 

 copious development of this latter organism took place in a vessel in 

 which he had been cultivating Stephanosphaera ; and that in so great 

 quantities, that the water resembled a green mucus, and in each drop 

 thousands abounded. This is then at least a possibly noteworthy coin- 

 cidence, and the circumstance, quantum valeat, is perhaps deserving of 

 this cursory record. 



A third developmental change of the primordial cells of Stephano- 

 sphaera, connected doubtless in some way with propagation, is that 

 which results in the formation of " microgonidia." Their development 

 is at first like that of the " macrogonidia" — that is, the division of the 

 primordial cells into two, into four, into eight, but not stopping here, 

 but again dividing into sixteen, and so on, and finally into an innume- 

 rable number of minute elongate fusiform quadriciliate cellules — the 

 "microgonidia." These do not at any stage secrete an envelope-cell, 

 but remain crowded together within the original envelope-cell, inside of 

 which they actively move hither and thither in an amazingly rapid and 

 energetic way, than which there is scarcely any more astonishing sight ; 

 these finally escape from the old envelope-cell by its rupture ; and losing 

 their cilia, coming to rest, and assuming a reddish colour, become de- 

 veloped by a series of self-divisions, and formation of special walls, into 

 structures somewhat like in form (and I believe in that only) to P>o- 

 tryocystis, or to Kiitzing's Microcystis or Polycystis; of these any 

 further development is unknown. It has been supposed that these mi- 

 crogonidia, as in Volvox, may be perhaps looked upon as spermatozoids, 



Op. cit., p. 169. 



