145 



we wonder at this Botiferon obtaining access to the interior of the 

 sphere, we wonder still more at seeing even the young spheres, while 

 yet within the mother- sphere, thus tenanted : especially as the cir- 

 cumference, both of mother and daughter, appears unbroken. On 

 careful examination, however, the parent Volvox shows places where 

 the monads are interrupted ; and I have thought that I could disco- 

 ver, in each case of a tenanted embryo, that its circumference had a 

 ragged point. 



The Volvox does not appear to suffer from the depredations of its 

 ungrateful guest ; for though half of its young embryos may be de- 

 voured, it glides along with as swift and as majestic a course as ever: 

 nor are the vibrations of its cilia intermitted, for any floating atoms 

 that lie in its track are hurled- away with impetuosity, the moment 

 they come within reach of this living whirlpool. 



In some spheres we find eggs with Notommata ; in some, eggs 

 alone. Perhaps the parasite is always hatched in a parent Volvox, 

 but the embryo globe is probably entered from without, and the No- 

 tommata is then expelled with it. The Notommatce frequently eat 

 their way out, and swim at freedom. 



Observing one, large with a nearly matured egg, in the globe of a 

 small Volvox, I opened the latter with a fine needle, and freed the 

 Notommata. This I placed in clear water, and added several Volvo- 

 ces of various ages, taking care that none contained a parasite. I 

 then watched its proceedings, to see if it would enter any one of the 

 globes ; but though, in the course of its swift and headlong rotation, 

 it now and then came into contact with a globe, and would arrest its 

 career to play over its surface, and even to nibble at it, it would pre- 

 sently dart away again ; not entering one in the lapse of several 

 hours. In the course of this time it deposited its egg loose in the 

 water, which probably it would not have done had I left it to follow 

 the dictates of its instinct. This egg differed greatly in appearance 

 from any that I had as yet seen in the interior of globes ; for whereas 

 they were perfectly smooth and translucent, showing the eye, the 

 jaws, and the ciliary motion as these were developed (see fig. g), this 

 (see fig. h) was opaque, and covered closely with short obtuse prickles. 

 The size of both was nearly the same, measuring T ^ by ifa of an 

 inch. Subsequently, however, I found several of the prickly eggs in 

 globes ; and in one, both a prickly egg and a smooth one. 



In one case I witnessed the evolution of a young Notommata from 

 a smooth egg ; it exactly resembled the parent. It remained long- 

 half hatched, without forsaking the egg, the anterior half of the body 



J TRANS. MIC. SOC. VOL. III. U 



