ALG.E. 125 



astonishing rapidity. The cells of the net, under 

 favourable circumstances, increase to six hundred 

 times the length, and two hundred and forty thousand 

 times the volume in a few weeks. Meanwhile the 

 mother-cell becomes more and more gelatinous and 

 ultimately melts away, leaving the young water-net 

 free and exposed, ready to commence life on its own 

 account. Thus much then, briefly, for the direct 

 production of young water-nets by the large gonidia 

 of a single mother-cell. 



As for the other method of reproduction by the 

 small gonidia, it takes place in cells indistinguishable 

 in form, size, and appearance from those which pro- 

 duce the large gonidia. The gonidia themselves may 

 be distinguished, not only by their smaller size, but 

 by a longer shape, a small red vesicle, and four long 

 cilia. They swarm out from the ruptured mother- 

 cell, move about very actively, often for three hours, 

 and then come to rest. The mother-cell, which con- 

 tains at length the small gonidia, does not expand 

 uniformly, 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 about most actively. The membrane of the 

 cell, emptied of its contents, docs not dissolve away 

 at once, but remains for a long time unchanged as 

 an empty coat. The swarming out always takes 

 place rather later in the day than the formation of 

 the nets, being in summer usually between seven and 

 nine, and in autumn between ten and two o'clock. 

 This swarming lasts for several hours, the active 

 condition being often observed late in the afternoon, 



