july — sept. 1857.] The Vohox Globator. 



309 



(era, and the other Volvocinece, each spherurle is, propely speaking, 

 not so much an individual as an association or family of individu- 

 als a sort of vegetable polypary." 



" The globe of Vohox is formed at its periphery of an infinitude 

 of very minute hexagonal cells attached to each other in the same 

 way as are the elements of an epidermic tissue. Each of the cells 

 is furnished with two motile cilia and may be compared with a 

 Chlamy do coccus. The green endochrome is suspended as it were, 

 in the cavity, being connected with the wall only by means of fili- 

 form processes. 



" Like all the Algge, the Volvocinece present two distinct modes of 

 reproduction ; but up to the present time naturalists have been ac- 

 quainted with only one of these, consisting in the repeated seg- 

 mentation of the constituent cells, and resembling the fissiparity of 

 Chlamydococcus and Gonium, or that of most of the Palmellacece. 



" The second mode of reproduction of Volvox requires a sexual 

 conjunction and is not observed indifferently in all individuals. 

 The spherules endowed with the sexual function, are distinguish- 

 ed by their volume and the more considerable number of their 

 component utricles ; they are generally monoecious that is to say 

 they enclose at the same time male and female cells although the 

 majority of their contents are neuter. The female cells soon ex- 

 ceed their neighbours in size, assume a deeper green colour, and 

 become elongated like a matrass towards the centre of the Volvox. 

 The endochrome of these cells does not undergo fission. In the 

 other cells on the contrary, which acquire the size and form of the 

 female cells, the green plasma may be seen to divide symmetrical- 

 ly into an infinity of very minute particles or linear corpuscles, as- 

 sociated into discoid bundles. These are furnished with vibratile 

 cilia, and oscillate, at first slowly in their prism, but the movement 

 soon becomes more active, and the bundles speedily break up into 

 their constituent elements. The free corpuscles are very agile, 

 and it is impossible to regard them as anything but true spermato- 

 zoids ; they are linear and thickened at the posterior extremity : 

 two long cilia are placed behind their middle, and the rostrum 

 which is curved like the neck of a swan possesses sufficient con- 



