HICK : KLEIN ON THE GENUS VOLVOX. 89 



(luction only. His Volvcx stellatus, with echinulate oospores, was 

 merely the female colony of V. globator^ and his Volvox aureus, with 

 smooth oospores, the corresponding colony of another species, whose 

 male colonies he regarded as generically distinct and named 

 Sphierosira volvox. In 1854 Stein recognised the distinctness of 

 tlie species with smooth oospores and named it Volvox minor, while 

 Cohn proposed the name of Volvox monoicus for Ehrenberg's 

 V. glcbalor, and V. dioicus for Stein's V. minor, being inclined to 

 regard both as sub-species of the old Linna^an Voh'ox globator. 

 Subsequently (1882), Drude cleared up the somewhat entangled 

 synonymy of these two species of Volvox, and sustained the claims 

 of Volvox aureus to stand as the name of the second species against 

 the later designations of Stein and Cohn. In the paper under 

 consideration Klein follows Drude in naming these forms of A^olvox, 

 V. globator and V. aureus respectively, and furnishes sufficient 

 details of the structure and life-cycle of each to enable us to see in 

 what respects they agree and differ respectively. 



Selecting what appear to be the most obvious and most pro- 

 nounced characters, the diagnosis of each species will run as follows : 

 Volvox globator Ehr. Volvox monoicus Cohn. 



Colonies : Asexual, globular ; Sexual, oval ; usually larger than 



those of V. aureus. 

 Protoplasts : Angular in the surface view and irregularly pro- 

 duced at the angles ; smaller and more numerous than 

 those of V. aureus ; contractile vacuoles 2-6, usually 4. 

 Connecting threads or processes : not sharply distinguished from 

 the protoplasts ; much thicker than the cilia. 

 Volvox aureus Ehr. Volvox minor Stein ; Volvox dioicus Cohn. 

 Colonies : Asexual, globular ; Female, globular*; Male, oval ; 



Female usually smaller than those of V. globator. 



Protoplasts : Nearly or quite circular in the surface view; fewer 



than in V. globator, but larger in size ; contractile vacuoles 2. 



Connecting threads or processes; sharply distinguished from the 



protoplasts ; as fine as the cilia. 



The connecting threads or processes here referred to are the 



strands of protoplasm which connect the protoplasts of the individual 



cells. In V. globator they are mere continuations of the processes 



of the protoplasts, and are comparatively stout ; in V. aureus, whose 



protoplasts are devoid of such processes, they^arise from the surface 



and are extremely fine filaments. Klein has raised again the 



question as to whether these threads are continuous, bringing the 



* In Spring a few are oval, and have a small nipple at the posterior end. 

 March 1890. 



