526 



SYSTEMATIC HISTORY OF THE rS^FUSOfllA. 



provided ^^dth a pair of cilia which are attached to the anterior extremity, 

 and some distance behind them with an eye-spot ; their progression is 

 vermicular from their extreme plasticity, and they keep up an incessant 

 flagellating movement with their ciUa. As yet, I have never seen any of 

 these free in the daughter bearing the spermatic cells when the former has 

 been outside the parent ; nor have I ever seen them fi^ee under any cir- 

 cumstances, except once, in the old Volvocc, when the daughter containing 

 the spermatic cells from which they had been developed had been partly 

 eaten up by Rotatoria. 



" This is the form of Volvocc Glohator which has been called Splia'rosim 

 Vohox by Ehrenberg ; and, like the daughters bearing the spore-cells, it 

 becomes liberated fi'om the parent before the speiinatic cells attain their 

 ultimate development, that is, before the groups of spermatozoids become 

 separated, not before they are formed. It is worthy of remark, too, that the 

 daughter bearing spermatic cells is never more than half the size of the spore- 

 bearing daughter, at least as far as my observations extend. 



*' Thus we have the spore-cells and the spermatic cells in different daughters ; 

 and as I have never seen them together in the same daughter, nor the 

 daughters respectively beaiing them in the same parent Volvox, out of some 

 scores of instances, I can come to no other conclusion than that the two 

 daughters meet after they have left their respective parents, when, both the 

 spores and the spermatozoids having become ripe for fecundation, indi^dduals 

 forming the groups of the latter separate, bui'st from their capsules into the 

 cavity of the daughter, and from thence find their way out into the water, 

 and then into the cavity of the daughter bearing the spore-cells, where they 

 become incorporated with the latter. 



*' Hence Volvox Glohator would appear to be dioecious, and not monoecious 

 as stated by Cohn ; and Sjjhcerosira Volvox not, strictly speaking, another 

 form of Volvox Glohator, but the spermatic form. Cohn, considering Volvox 

 Glohator and Volvox stellatus the same species, has taken his fecundating 

 character from the spermatic form of the latter." 



The spermatic groups above described. Carter subsequently remarks, con- 

 stitute in all probability Ehrenberg's genera Syncrypta, Synura, and Uro~ 

 glena. 



Sph^eosiea Volvox. — Corpuscles 

 pale gi'een, of nearly a globular shape, 

 enveloped in a common mantle. Eye 

 bright red. The cluster resembles a 

 great ball of coi-puscles, containing small 



compressed clusters within it. Found in 

 considerable numbers in company with 

 Volvox Glohator, and often attains its 

 size. Sometimes found by itself. 



Genus YOLYOX (XX. 32-47) (Part I. p. 180).— The genus Volvox, which 

 is the type of the family Yolvocina, was instituted by Linnaeus, and promul- 

 gated to the world in 1 758, in the tenth edition of his ' Systema Xatm^ae.' As 

 fii*st described by him, the two species V. Glohator and V. Chaos comprehended 

 all known Infusoria, excepting eleven of the tribe Vorticella, which were 

 separated from them, under the denomiaation of Hydra. In his twelfth edi- 

 tion (1766) of the same work, he distributed the Infusoria into foiu^ genera, 

 viz. Vorticella, Volvox, Hydra, and Chaos. 



Volvox is characterized by the aggregation of its cells or gonidia over the 

 internal surface of a transparent lorica or common envelope ceU, of the form 

 of a hollow globe. Each corpuscle or gonidium possesses a red speck and two 

 filaments, which protmde beyond the siu-face of the lorica so as to give the 

 whole globe the appearance of being covered with ciha. The mode of 

 increasing by a sort of internal gemmation is characteristic of the genus. 



