192 THE PHENOMENON OF 



now too small, being peeled off in little strips By this 

 expansion the cell-membrane is removed to a little dis- 

 tance from the layer of macrogonidia previously lying close 

 upon it, and these, now gaining space, commence a more 

 active tremulous motion, soon uniting together into a 

 new net inside the mother-cell membrane, and in this 

 combination settling to rest. The young net enclosed 

 by the membrane of the mother-cell now grows rapidly, 

 the mother-cell membrane continues to expand for a 

 short time longer, becoming at the same time continually 

 less distinct, and by the second day it has entirely 

 vanished. In those cells, on the other hand, containing 

 microgonidia, the cell-membrane does not expand uni- 

 formly, but forms a bulging enlargement, at one or other 

 part where the cuticle is torn, which bursts and lets out 

 the microgonidia in a dense swarm, moving most actively. 

 Emptied by the swarming out, it remains unchanged, 

 and is for a long time distinguishable as an empty coat, 

 a proof that the more rapid solution of the net-forming 

 mother-cell is produced by internal causes. Other cells 

 which do not arrive at fructification, never exhibit the 

 process of softening. While, under favorable circum- 

 stances, the entire process of vegetation of the Hydro- 

 dictyon net is completed in 3 4 weeks, in which 

 time the individual cell is enlarged (longitudinally) more 

 than a hundred-fold (sometimes even 4 5 hundred- 

 fold), other nets, in unfavorable conditions, exhibit 

 a slower development, vegetating for four or five months 

 without attaining the normal dimensions. In the cells 

 of such retarded nets, never attaining to fructification, 

 we observe a proportionately thicker and very firm cell- 

 membrane, which exhibits in the sectional view a delicate 

 transverse striation (pore canals ?) which I never could 

 detect in normally developed cells.* 



* (This striation seems analogous to that sometimes occurring in liber- 

 cells of certain Phanerogamia, as first described by Schacht. See a notice 

 on this point (by the present translator) in the ' Journ. of Microsc. Science,' 

 vol. i, p. 233, (1853.) A. H.) 



