230 THE PHENOMENON OF 



b. The outer layers of the cell-membrane become, 

 sooner or later, cracked and peeled off, which takes place 

 either by rapid growth of the cell, not inclusively of the 

 outer membrane, as in the paraphyses of Diphyscium 

 (p. 177), or through more or less abundant secretions of 

 jelly alternating with the lamellae of the cell-membrane, 

 as already mentioned in the description of the phenomena 

 of "skinning" in Glcsocapsa, Glceocystis, Pleurococcus 

 miniatus, Chroococcus decorticans (p. 182), Urococcus 

 (p. L78), and Schizochlamys (p. 181). The last-named 

 example, each new membrane being thrown off by a regular 

 dehiscence before the new one is formed, connects this 

 group of cases very clearly with the succeeding series. 

 The cell, as it were, new-born after every "new skinning," 

 is not regarded each time as a new cell, simply because 

 its character does not suffer any perceptible change. 



2. Reconstruction without division in the transition 

 to fructification, or retrogresswely from this to germi- 

 nation. 'In both cases the vital process of the cell 

 acquires with the reconstruction a new direction of the 

 physiological activity, an altered destination ; in the 

 former case, a transition from the vegetative growth to 

 the swarming condition of the gonidium, or the sleeping 

 condition of the spore ; in the latter, on the contrary, 

 from the sleeping condition to the vegetative develop- 

 ment. If in such a transition no throwing off of a 

 membrane formed in an earlier condition takes place, as 

 is usual in the passage of swarming gonidia into germi- 

 nation,* and occasionally happens in the transition of 



* What becomes of the very rapidly vanishing cilia in this transition I 

 have not been able to make out with certainty. According to Unger, they 

 are not thrown off in Vaucheria, but drawn m and smootheued down. In 

 Aphanochcete repens I once saw, on a gonidium passing into the state of rest, 

 in place of the large cilia, two extremely short processes, which exhibited a 

 jerking movement, (alternately stretching forward and retracting,) for a 

 short time longer. The gonidia of Characium Sieboldii exhibit, after they 

 have already attached themselves by their ciliated extremities, a tremulous 

 motion lasting for almost a quarter of an hour, and evidently commencing 

 in the delicate stalk. These phenomena certainly speak rather for a retrac- 

 tion than for a casting off of the cilia. 



