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the development takes place in a peculiar way. The pecu- 
liarity is twofold. First, instead of some half-dozen of the 
gonidia being selected for fission and development into spheres, 
as in Volvox, in Sphcerosira fully one-half of the entire number 
contained in the organism are developed. Then there is, 
secondly, a difference in the direction of fission. In Volvox, as 
already seen, this fission not only takes place along various 
planes vertical to the surface, but also in others that are hori- 
zontal to and parallel with it. In the Sphcerosira we have the 
former system of cleavages, but not the latter. Hence the 
separate protoplasms are grouped in a single plane with their 
long axes vertical to the surface of the tabular disk. This 
limitation of the direction of cleavage thus reduces itself to a 
comparatively small matter, and appears to me not only to 
indicate no generic distinction, but not even a specific one. 
It merely exhibits one of the incidental variations in growth 
and development so common amongst these lower algae, and, 
regarded physiologically, has no special value ; least of all does 
it appear to bear any relation to the sexual reproductive pro- 
cesses so common amongst the higher cryptogamia. 
