264 THE PHENOMENON OF 



ment of a dense crowd of people in which no one can 

 leave his place. The signal for freer and more active 

 motion is given by the processes taking place about this 

 time in the membrane of the mother-cell. The cell- 

 membrane has begun to thicken even in the second stage 

 of the formation of the gonidia, and the swelling-up 

 made still further progress in the third, but the resist- 

 ance of the cuticle hinders the extension of the circum- 

 ference of the cell-membrane. This obstacle is now 

 removed by the cuticle cracking, first in one, and soon in 

 several places, which gives the cell-membrane, now 

 becoming soft and limp through the swelling-up, room to 

 expand. This is the epoch in which the movement of 

 the gonidia changes, either simultaneously throughout 

 the cell, or more frequently gradually spreading from the 

 spot where the first dehiscence of the cuticle occurred, 

 into a lively trembling and jerking, which Treviranus not 

 inaptly compares with the ebullition of boiling water. 

 But even in this very rapid motion the actual locomotion 

 of the gonidia is extremely slight, so that, for example, 

 free spaces, such as occur in cells where vacuities existed 

 in the mucilaginous layer, are not filled up by gonidia. 

 In the macrogonidia, destined to form nets, the motion 

 stops here; in the microgonidia, on the contrary, a 

 whirling is added to the trembling motion. While, 

 namely, up to this time, the whole mass of microgonidia 

 had retained their peripherical position, representing as a 

 whole the form of a sac, corresponding to the form of the 

 mucilaginous layer, even in their movement, this strange 

 bond is now dissolved, the gonidia leave the periphery, 

 and whirl about in varied intermixture through the 

 whole cavity of the cell, till at length, through the 

 bursting of one or more bulging protrusions of the cell- 

 membrane, they leave the cell in a dense swarm, and 

 continue the swarming motion for a long time in freedom. 

 Both the macrogonidia and microgonidia exhibit various 

 peculiarities, during the period of motion, which were 

 not perceptible before its commencement. The macro- 



