THE PHILIPPINE 



Journal of Science 



Vol. XV DECEMBER, 1919 No. 6 



CAMPBELLOSPHAERA, A NEW GENUS OF THE 

 VOLVOCACEAE 



By Walter R. Shaw 



Of the Department of Botany, College of Liberal Arts, University of the 



Philippines, Manila 



TWO PLATES AND ONE TEXT FIGURE 



Mixed with several other species of Volvocaceae in living 

 material collected at Pasig in July, 1914, there was a globular 

 plant resembling in many respects Volvox carteri Stein. I 

 regarded it as representing a new genus, and under the specific 

 name carteri there accumulated in my notebook, in the course of 

 months, a mass of data consisting largely of measurements and 

 cell counts supposed to be descriptive of various stages in the 

 life history of the plant. In November, 1916, when a written 

 account of the new genus was nearly completed from the notes, 

 a night session with a living specimen supposed to belong to the 

 species revealed a difference in behavior inconsistent with the 

 most distinctive character of the genus, thus making it evident 

 that my description was a composite, embracing species of two 

 genera. Consequently it has been my task to disentangle the 

 descriptions of these species. 



The plant which is the subject of this paper has globular, 

 biciliate protoplasts with no protoplasmic connections. It has 

 gonidia which are differentiated from the somatogenic cells at 

 an early stage in the development of the embryo, and they 

 become so large, before dividing in their turn, that the species 

 may be called megalogonidiate. But the distinctive character 

 of the genus is a migration of the gonidia from the outside to 

 the inside of the embryo. In the bowl stage of the embryo they 



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