MICROSCOPIC WONDERS 15 



movement have been discovered ; even the highest power lens 

 and the most carefully arranged light effects give no clue to 

 this mystery ; and one can only imagine that it is by means 

 of some most minute hairs, so fine and so transparent that 

 they are ultra-microscopic, or else by some other physical or 

 chemical means, unless we take it for granted that these most 

 interesting " plants " have a means of movement that has no 

 similarity in the higher world. 



Volvox globator may be said to resemble a tennis ball -g^jth 

 of an inch in diameter ; in fact its behaviour is so much like that 

 off an animal, that it is a moot point as to whether it should 

 not be classified as such. 



It is not a single-celled plant as a Desmid, but a colony of 

 cells joined together by strands of protoplasm, in the form of 

 a round net, the knots being the individual cells. 



Each little cell is furnished with a pair of minute hairs, 

 known as cilia, which are most energetically waved. 



It may strike the reader as extraordinary that the volvox 

 should move in any direction whatsoever, as we can hardly 

 imagine that each of these minute cells co-operates with the re- 

 mainder, but it is probably due to their independent action 

 that the volvox rolls through the water in such an original 

 way. 



Strangely enough, one often notices that inside the volvox 

 itself some other creature is living a perfectly free life, seem- 

 ingly indifferent to its destiny. This rather goes to show that 

 the volvox either contains water, or comparatively non-viscid 

 material. 



Volvox multiplies by both asexual and sexual methods. 



In the case of the asexual, daughter cells are formed similar 

 to the parent, and the juveniles roll over and over inside the 

 parent in a most unfilial manner, and when the adult volvox 

 thinks that the joke has gone far enough it breaks open in the 

 gentlest way, and the daughter volvoxes, leaving their parent, 

 start on an independent existence. 



The second method is rather more interesting. Some of the 

 cells become changed in shape, and form respectively anthero- 

 zoids and oospheres, and then after a short time the antherozoid 

 opens, and a large number of animal-like objects swim out and 

 find their way towards an oogonium, into which they hurry. 

 A spore case is then formed, and, as usual, ends the following 

 year in a fresh generation of these most interesting plants. 



If there should be doubt that each little cell forming the 

 net is an independent object, one has only to crush a volvox 

 under a cover glass to see that such is the case ; for each little 



