OF THE PHYTOZOA. 173 



orifices through which the cilia previously passed out into the water may 

 now be observed in the common envelope-cell, as minute points surrounded 

 by a thickened border. 



" Immediately, after that, it is seen that the newly-formed secondary cells 

 have developed their ovvn cilia; for the yoimg generations formed in the 

 interior of the parent- envelope now begin to move and to roll over like a 

 wheel, so far as the confined space allows of this. In consequence of this 

 movement of the eight small wheels rotating in the interior of the common 

 envelope- cell, which constitutes a very pretty object, the parent-cell soon 

 becomes enlarged and attenuated at certain points ; the cellulose of which it 

 is composed appears to be transformed into soluble jeUy, and soon afterwards 

 one after the other breaks through out of the common envelope and revolves 

 fi'eely and independently in the water, according to the same laws as the old 

 spheres, but more actively and energetically. The young Sfej)hanoSjphcera 

 exactly resembles a green wi-eath composed of eight small cylinders, upon 

 which by itself no envelope and cilia can be detected (XIX. 42, 48, 49) ; but 

 if killed with iodine, the eight primordial cells are seen to be siuTounded by a 

 common envelope-cell in the form of an exceedingly delicate membrane, — only 

 this lies in all parts almost immediately upon the green globes, so that it 

 follows the waved outline they produce, and in its total form resembles a flat 

 spheroid mth eight notches on its border ; it is perforated by the cHia, which 

 go off in pairs from each of the primordial cells ; and two chlorophyll-utricles 

 are already distinguishable in the latter. By degrees the envelope-cell is 

 hfted up by the endosmotic absorption of water ; its surface becomes smoothed 

 out, and it appears cii'cular in the polar view ; on the other hand, it retains 

 for a longer time the form of an almost tabular spheroid, and hence presents an 

 ellipse in the equatorial view (XIX. 58) ; finally it expands uniformly in aU 

 directions and thus acquii-es its normal spherical form, while at the same 

 time it becomes considerably thickened. This whole process of propagation 

 is completed duilng the night ; and on bright days Stephanosphcercn are rarely 

 seen in coiu^se of division at sunrise ; on dull days they may be observed in 

 this condition in the first part of the morning. 



" The primordial cells, however, not unfrequently come to a standstill in 

 the stage of division of the second generation, so that they only separate into 

 four secondary cells ; these at once develope clLia and an envelope-cell, with- 

 out dividing a third time, and make their exit from the parent-envelope in 

 this condition. Here therefore only the first generation of each primordial 

 cell is a transitional generation, the second already a permanent generation. 

 Hence arises the circumstance that we often find, among other eightfold Ste- 

 phanosphcera-glohes, some in which the envelope-cell encloses only four pri- 

 mordial cells standing at equal distances, which in other respects behave in 

 the ordinary manner. 



"It is still more frequently observed, when the primordial cells have 

 already become constricted into four secondary cells and are beginning to 

 divide again iuto eight, that this j)rocess of division is not perfectly completed 

 in aU foui' portions, but that the young Stephanosphcera abeady becomes free 

 and developes the envelope-cell, although one or other of the four quadratic 

 segments of the sphere has become constricted but not parted off. Hence origi- 

 nate monstrous forms, since the general envelope-cell then encloses only 

 seven primordial cells ; but in these cases it is always observed that one of 

 them is distinguished by most curious prolongations or mucous filaments, that 

 it appears twice as large as the rest, that it contains four chlorophyll-utricles 

 instead of two as is usual, and that it is also more or less constricted in the 

 middle. AU this furnishes proof that here one secondary cell of the second 



