184 GENEEAL HISTOHY OF THE liS^FUSORIA. 



have determined the reality of another mode of reproduction besides fission, 

 as surmised (Ann. Sc. Nat. and Comptes Rendus, 1856). The abstract of 

 this most interesting paper is translated in the J. M. S. 1857, p. 149 : — " The 

 second mode of reproduction of Volvox requii'es a sexual conjunction, and is 

 not observed indifferently in all indi^dduals. The sj)herules endowed with 

 the sexual fimction are distinguished by their volimie and the more consi- 

 derable number of their component utiicles : 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 exceed their 

 neighboui's in size, assume a deeper green colom-, and become elongated like 

 a matrass towards the centre of the Volvox. The endochrome of these ceUs 

 does not undergo fission. In other cells, on the contrary, which acquire the 

 size and form of the female ceUs, the green plasma may be seen to divide 

 symmetrically into an infinity of very minute particles, or linear corpuscles, 

 associated into discoid bundles. These are fiu'iiished with ^ibratile cilia, and 

 oscillate at fii^st slowly in their prism ; but the movement soon becomes more 

 active, and the bundles speedily break up into theu^ constituent elements. 

 The fi'ee corpuscles are very agile, and it is impossible to regard them as any- 

 thing but true spermatozoids ; they arc linear and thickened at the posterior 

 extremity ; two long ciha are placed behind theii^ middle, and the rostrum, 

 which is curved like the neck of a swan, possesses sufficient contractility to 

 execute the most varied movements. These spermatozoids, so soon as they 

 are they are able to disperse themselves in the cavity of the Volvox, quickly 

 crowd aroimd the female cells, into which they eventually penetrate ; arrived 

 there, they attach themselves by the beak to the plastic globule, destined in 

 each ceU to form a spore, and with which they are gradually incoi-porated. 

 Fecundation having been thus effected, the reproductive globule becomes enve- 

 loped successively by an integument exhibiting conical pointed eminences, and 

 by an interior smooth membrane ; the chlorophyll which it contained is now 

 replaced by starch grains, and a red or orange-coloiu-ed oil. This is the con- 

 dition of the spore at matmity ; and occasionally forty of these bodies may be 

 counted in a single globe of Volvox. The germination of these reproductive 

 bodies has not yet been observed, so that their history cannot be regarded as 

 complete ; but from analogy it may in the meanwhile be assumed that they 

 germinate in the same way as do the spores of (Edogonmm, Splueroplea, and 

 other Algae belonging to the same order. It may be maintained, moreover, 

 as certain that the Splicerosira volvox, Ehr.,is nothing else than a monoecious 

 Volvox glohator ; that his Volvox stellatm is also V. glohator, obseiwed at the 

 time when it is filled with stellate spores ; and lastly, that his V. aureus 

 differs from the other forms of the same species, simply in the smooth [and 

 coloured] condition of the spores;" 



FAMILY lY.— YIBRIONIA. 

 (Plate XYIII. 57 to 69.) 



This family foUows, in Ehrenbei'g's system, the VolvocinecB ; yet, by reason 

 of the extreme simplicity of stmcture of the beings composing it, it should, in 

 any attempted natiu'al system, be placed even below the Monadina. 



The distinguished author of the Infuslonstluerclien attributed an animal 

 nature to the Vihrionia,Q.Tidi although obliged to confess his inability to detect 

 any internal organization, nevertheless argued, from analogy, that a polygas- 

 tric structui-e was to be presumed, and that their movements were voluntary, 

 and of themselves sufficient proof of animaHty. In Bacterium triloculare, 

 indeed, Ehrenberg believed he saw an internal granidar ova-mass, a vibratile 



