xv - « Shaw: Campbellosphaera 5H 



Cuter wall of oospore reticulately wrinkled or ridged, diameter, 

 about 34 to 42 /z. Spermatozoids, about 6 n long. 



Habitat. — Fresh-water ponds, near Manila, Philippine Islands. 



COMPARISON WITH PREVIOUSLY DESCRIBED SPECIES 



The earliest described Volvox with megalogonidia similar to 

 those of Campbellosphaera is Volvox carteri Stein (78), which 

 was described by Carter from Bombay, India, in 1859, under 

 the name Volvox globator. Carter's description presented the 

 large gonidia, one of which is shown in his fig. 4. That these 

 gonidia must be differentiated early in the ontogeny is evident 

 from the size which they reach before f>irth as shown in his fig. 

 1. Points of difference from Campbellosphaera appear in this 

 figure ; namely, the globose form of the coenobia, and the practi- 

 cally uniform size of the gonidia in each daughter. This uni- 

 formity is further shown in his fig. 3, in which the gonidia have 

 reached the maximum size before segmentation. Carter re- 

 presented his species as having somatic cells with globose or 

 ovoid protoplasts, in which respect it is like our new genus. 



A variety of Volvox carteri was described by Powers ('08), 

 from Missouri, under the name Volvox weismannia. Powers 

 failed to perceive that what Carter, in referring to his fig. 4, 

 called a "daughter" was in reality a gonidium and identical with 

 one of the reproductive cells which Powers called "primary sex 

 cells" and "ova." Powers did, however, clearly recognize and 

 emphasize the fact that these reproductive cells are differentiated 

 at an early stage in the development of the embryo. The semi- 

 diagrammatic nature of Carter's drawings masked the symmetry 

 of the arrangement of the gonidia in the coenobia, which Powers 

 noted as characteristic of his species. Powers supplied enough 

 information on the embryos to show that the species lacks a 

 migration of the gonidia such as is characteristic of Campbello- 

 ijpliaera. He showed clearly that his species also forms "dwarf 

 male" coenobia, a point of difference from C. obversa. He over- 

 looked the distinction between asexual and female coenobia. 

 though he figured embryos of both kinds [Powers ('08), Plate 

 26, fig. 45 asexual, and fig. 47 female]. 



In my own collections, made in the neighborhood of Manila, 

 on many of the eight hundred thirty-four slides of Volvox in 

 my cabinets, and among the one hundred fifty photomicrographs 

 of Volvox that I made in 1916, there is a multitude of forms 

 and stages of Volvox carteri, which promises to afford material 



