VOLVOX FOR LABORATORY USE 



BERTRAM G. SMITH 



In providing a supply of Volvox for class use late in the fall, 

 difficulty has been experienced in two respects: in keeping the 

 material alive in the laboratory as long as desired, and in getting 

 specimens containing sperm and ova. Inquiry reveals the fact 

 that others have had the same trouble. I have recently been able 

 to overcome both these difficulties, and at the suggestion of Dr. 

 H. H. Newman have recorded the method in some brief notes. 



Species. — So far as known, the only species of Volvox that has 

 been found in the vicinity of Ann Arbor during the late autunm is 

 Volvox aureus Ehrenb. It is not very abundant, and 1 have never 

 found it in the sexual stage at the time it was collected. It (occurs 

 in small glacial pools containing Riccia and duckweed. 



During the early spring Volvox glohatar Linri., and no other 

 species, occurs in great abundance in the same pools that later con- 

 tain Volvox aureus. I have occasionally found it in the sexual 

 stage when collected. 



By the latter part of June Volvox glohator has become quite 

 scarce, and V. aureus has begun to appear. During the early 

 part of July the two species exist in the same habitats, but neither 

 is very abundant. 



Since Volvox is so widely used for laboratory work by beginning 

 classes, the marked specific differences are matters of importance. 

 Volvox glohator is the form described in text-books bur the de- 

 scription is far from being applicable to V. aun iis. Since the latter 

 may at times be the only species available, it may be profitable to 

 call attention to the differences between the two species, for it is to 

 be suspected that Volvox aureus is sometimes used without its 

 species being recognized. 



Volvox glohator is considerably larger than F. aiinnis: its somatic 

 cells are more numerous and compactly arraiiired. The somatic 

 cells of glohator are angular and connected l»y \erv stout proto- 

 plasmic strands; the somatic cells of aureus are round when seen 



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