OF THE PHTTOZOA. 195 



or embryonic cells, and that during this time the chlorophyll passes into red 

 grains, and subsequently disappears, while the organism is secreting a capsule 

 around itself, and its original cell-wall passes into a tough spherical ovisac, so 

 to speak. But what becomes of this, if it be the result of impregnation, or 

 what the process of impregnation is like, or when it takes place, is for future 

 discovery to determine." 



ChJoroc/onium eiichlorum (PI. XX. 15-21) was the subject of an interest- 

 ing observation by Weisse (Wiegmann's Archiv, 1848), who thought he had 

 demonstrated in this species propagation by ova or germs, and, in fact, elu- 

 cidated in it the development of microgonidia, by repeated acts of self-fission 

 of the contents, just as in the spores of Algae. For instance, he described the 

 contained green matter of the fusiform being fii'st to contract in some mea- 

 sure upon itself (XX. 16), then to exhibit a constriction followed by a line 

 of division into two portions, which, by subsequent redivisions, resolved the 

 whole into a nodular mass resembKng a bunch of grapes (XX. 17-18). 

 This grapebunch-like mass possessed a certain mobility within the enclosing 

 integument; and as the process of development proceeded further, its se- 

 veral particles or segments displayed a movement among themselves, which in- 

 creased in extent and vigour until the external envelope gave way before it, 

 and permitted their escape in the form of so many distinct particles or beings 

 (gonidia) endowed with ciliary filaments, whereby they kept up an active 

 movement in the surroimding water (XX. 21). The young forms produced 

 exhibited active movements within the parent- cell, and at one stage prior to 

 theii' discharge, when connected together in heaps, resembled Uvella Bodo. 

 On the ruptui^e of the cyst they escaped freely into the water with the fig-ure 

 of Chlorogoniwn. 



Schneider has also some remarks on this genus {A. N, H. xiv. p. 326). 

 He could discover no decided red speck, although as many as twelve reddish 

 spots were distributed over the surface of the green mass ; a contractile vesi- 

 cle, moreover, eluded his search. Of the mode of propagation he reports that 

 '' division takes place in the interior of the investing membrane, in exactly 

 the same manner as in Polytoma. The number of individuals produced is 

 never less than four, but often as many as thirty- two ; in the latter case they 

 are very small, but always resemble the parent in other respects. A spheri- 

 cal state of rest also occui'S. It appears that, when the requisite conditions 

 are present, the young proceeding from the division of the parent pass into 

 this state immediately after they are set free, — their soft investing mem- 

 brane probably rendering them fitter for this purpose. The contractions 

 which then take place are probably the same that were observed by Ehi^en- 

 berg. In other respects I have found the form unchangeable ; and Clilo- 

 rogonium must consequently be separated from the Astasicm, amongst which 

 it has hitherto been arranged. On the addition of iodine, only a few blue 

 granules are to be seen in the fusiform individuals ; the green spheres, on the 

 contrary, which are completely filled with green granules, acquire a deej^ blue 

 colour with this reagent : if the colouiing-matter be destroyed by means of 

 concentrated sulphimc acid, the granuifes are dissolved, and on the addition of 

 iodine, a beautiful blue colour is produced. By long keeping, the green of the 

 cyst passes to red. The cysts are not to be roused from their toi^oid condi- 

 tion by the production of fermentation. I have, however, observed their re- 

 vivification under other circumstances ; but my materials are insufficient to 

 enable me to describe the mode of reproduction of the investing membrane 

 and filaments, which would certainly be interesting. The conditions required 

 for the existence of Chlorogonium are apparently quite different from those of 

 Polytoma : the former did not multiply abundantly in infusions imtil the 



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