144 GENERAL HISTORY OF THE INFUSORIA. 



general features undistinguishable from Chlamydococcus under similar forms. 

 These escaping internal cells were divided into two, four, eight, and sixteen 

 parts ; and it was noticed that the variety which came forth with only two 

 gonidia was surrounded by a swarm of from ten to twenty much smaller 

 gonidia, which were identical in all appearance with those resulting from 

 di\dsion into sixty-four parts. But the cells divided into two segments were 

 not the only ones so surrounded by microgonidia ; for in two or three instances 

 a few were found around and adhering to the inner cell of those divided into 

 four gonidia. 



'' It was also observed that the two-division did not always come forth in 

 one cell, but that sometimes this was also divided, so that each gonidium had 

 its proper cell. The foiTU of the macrogonidia or female cells did not differ 

 from the internal cell of the parent, except in being a httle smaller, — while 

 the microgonidium, which was not more than l-7th of the diameter of the 

 macrogonidium, and therefore very small, appeared, though equally green, and 

 provided with an eye-spot, to have only one cilium. I cannot help thinking, 

 however, that, with a higher power, I might have seen two." 



The purpose fulfilled by the contact of the microgonidia with the macro- 

 gonidia, Mr. Carter concludes to be that of impregnation ; for he observed 

 one of the former, as a spermatozoid, fix itself to one of the latter (the spores 

 or female cells), and gradually become incorporated with it. The microgo- 

 nidium, after having so attached itself, assumed a conical or peg-top shape, 

 and thus appeared to gradually squeeze itself into the macrogonidium. 



This mode of impregnation, thus directly observed by Mr. Carter, is the 

 copy of that the same observer witnessed in Eudorina (Pcmdorina), and of 

 that first noted by Cohn in Volvo a\ He, moreover, believes that it obtains 

 in the case of Trachelomoiuis, for he '^ has often seen the largest Trachelo- 

 monad of a pool divided up into a group of apparently sixteen cells within 

 the lorica ; and this may account for the myriads of three to four smaller 

 sizes that are frequently found together in this way. The latter certainly 

 appear in a green form first ; that is, without the lorica, which gradually 

 becomes supplied afterwards. Thus, impregnation also in the Trachelomo- 

 nads may take place like that seen in Eudorina, after the parent-cell has 

 undergone division within the lorica." (See Part II., Systematic History of 

 Cryptomonadina. ) 



FAMILY III.— YOLVOCTNE^ OR YOLYOCINA. 

 (Plates XIX. XX.) 



This is the most important and most interesting family of the Phytozoa. 

 The genera enumerated in it by Ehrenberg were Gyges, Pandorina, Go- 

 nium, Syncrypta, Synura, Uroglena, Eudorina, Chlamydomonas, Sphwrosira, 

 and VoJvox, The name is derived from the rolling (volvere, to turn) motion 

 of the genus Volvox, which is typical of the family. Ehrenberg was the 

 first rightly to appreciate the tme nature and compound structure of the 

 principal genera as the aggregation of numerous monadiform beings in a 

 common polypary-like mass. He correctly described the several individuals 

 as resembhng Monads in most particulars of their organization, but was so 

 carried away beyond this simple natural statement by his pecuhar views of 

 structure, as to describe them as having an unvarying body, without other 

 external appendages than a pair of cilia or filaments, and internally several 

 digestive sacs but no true alimentary canal, green ova, two rounded seminal 

 glands, a contractile (spermatic) vesicle, and eye-specks indicating the exist- 

 ence of sensation. The substance connecting the several beings, and in 



