OF THE VOLVOCJNA. 



5i: 



Genus PANDOEINA (XIX. 59-69) (Part I. p. 157).— Destitute of eye- 

 speck and tail, but provided with a globular lorica and a slender filament. 

 During self- division the creature acquires the appearance of a mulberry. 

 Transparent vesicles occur in one species : two exhibit green, and a third 

 colourless granules. 



Dujardin esteems the presence of the red speck to be insufficient to distin- 

 guish Eudorina as a genus distinct from Pandorlna -, and most recent observers 

 agree with him. 



It has been shown by Braim {Rejuvenescence, Ray Soc. 1853, pp. 169-209), 

 as well as by others, that Ehrenberg was in error in assigning a single fila- 

 ment only to Pandorina, and no eye-speck — since two flabella extend from 

 the more pointed extremity of the being, and close to their base is a brownish- 

 red speck. 



Prof. Henfrey details {M. T. 1856, p. 49) the characteristics of Pandorina 

 much more fully, and corrects the errors into which Ehrenberg fell. He 

 assumes it to be a plant, and thus describes it : — " Pandorina. — Frond a mi- 

 croscopic, elhpsoidal, gelatinous mass, containing, imbedded near the peri- 

 phery, sixteen or more biciliated, permanently active gonidia, arranged in 

 several circles perpendicular to the long axis of the frond. The gonidia, al- 

 most globose, with a short beak-hke process, a red spot, and a pair of cilia 

 which project through the substance of the frond to form locomotive organs 

 upon its surface. Reproduction : 1. By the conversion of each gonidium 

 into a new frond within the parent mass. 2. By the conversion of the go- 

 nidia into encysted resting spores, which are set free, and (?) subsequently 

 germinate to produce new fronds." The genus more closely resembles Ste- 

 l^lianosplioera than any other of the family. 



Pandobina Moriim (Volvox Morum, 

 M.) (xix. 59-69). — Body simple or mul- 

 tipartite, enclosed within a simple lorica. 

 Colom* green ; filament twice as long as 

 the body. In water with Lemnse and 

 Confervae. Size of individual 1-1150", 

 cluster 1-120". Some individuals broken 

 from the cluster by Ehrenberg have not 

 been above one-third the former mea- 

 surement. 



P. Morum is much more satisfactorily 

 and correctly described by Mr. Henfrey, 

 thus : — " Fronds hyaline, from about 

 1-80" downwards. Gonidia either 16, 

 and then aiTanged into cireles of 4; or 32, 



and then in 5 circles — 2 at the poles, of 

 4, and the intennediate 3 of 8 gonidia; 

 which, in the perfect form, stand near 

 the periphery, and wide apart. In the 

 forms which produce the resting-spores, 

 the gonidia are crowded together in the 

 centre. The gonidia are green ; but the 

 contents of the resting-spores, after they 

 have become encysted, are converted 

 into oily and granular matter of a bright 

 red colour." 



P. hi/alincL — Form globular. In the 

 Nile with Confervte, and is a doubtful 

 species. 1-5760". 



Genus GONIUM (XIX. 32-37; Part I. p. 152).— Deficient both of eye- 

 speck and tail ; lorica simple ; in the process of self-division, form regular four- 

 cornered tablets or plates. The lorica (a lacerna) of each individual (as is seen 

 after its separation) is nearly round ; and the organism can cast it off and form 

 it anew. In one of the species (6r. Pectorale), two vibratory filaments are 

 placed at the mouth as organs of locomotion, &c. ; in the other species these 

 have not been observed. Vacuoles are seen within G. Pectorale ; and a red 

 speck (produced probably by refracted light) at the base of the filaments has 

 been conceived by Ehrenberg to indicate the mouth. 



Cohn's elaborate account furnishes the follovving additional notes on Go- 

 nium {Eiitwick. p. 179 ; and Part I. p. 152) : — The quadrate tablets consist of 

 sixteen polygonal (mostly hexagonal) cells, united together by tubular prolon- 

 gations from their angles, the whole being siuTOimded by a common gelatinous 



