XV, 6 



Shaw: Campbellospkaera 



509 



gonidium. These embryos are all in the same stage. The same 

 specimen is shown in fig. 16 on a smaller scale for comparison 

 with fig. 17. 



The separation of the gonidia in the daughters is shown in 

 Plate II, fig. 17, a mother coenobium (specimen 29) containing 

 six daughters and one gonidium. In all of the daughters the 

 gonidia have become separated, and they can be counted by fo- 

 cusing the microscope. The number in each case is eight. In 

 this stage the species is not easily distinguishable from Volvox 

 carter 'i Stein. 



The variation and graduation in size of the gonidia in the 

 same coenobium, and the consequent gradation in advancement 

 of sister embryos, may be practically lacking, as shown by figs. 

 15 and 17 of Plate II. On the other hand, a multitude of speci- 

 mens can be found with a gradation as pronounced, and an 

 arrangement as symmetrical, as is shown in Plate II, fig. 14, 

 which shows an asexual specimen (No. 30), containing six 

 gonidia arranged in three alternating pairs. This is from slide 

 1 of the pond J material. 



The number of somatic cells estimated to occur in the speci- 

 mens described, together with the number of reproductive cells 

 counted in each case, are given in Table I. 



Table I. — Number of cells in Campbellospkaera obversa. 



Asexual coenobia. 



Specimen No. 



12__„ 



1 



11 



25 



Type „. 



10 



22 ...- 



2 



26 



3 



4 



23 



6 .... 



7 



5 



25 » Daughter 



168743 2 



Somatic 

 cells. 



Repro- 

 ductive 



cells. 



Sexual coenobia. 



Specimen No. 



24 



23 • Daughter . 



8 ; 28* Daughter- 



Somatic 

 cells. 



2,960 

 2,660 

 8,460 

 2,360 

 2,330 

 2,300 

 2,200 

 1,920 



1,400 

 1,250 



Repro- 

 ductive 

 cells. 



645 



