ALGAL CULTIVATION PROBLEMS 13 



cially of the larger algae, it is true that for many of the plants at 

 present under consideration, such specimens fail to preserve the 

 critical taxonomic features such as flagella length and position, 

 number and position of contractile vacuoles, relation of flagellar 

 plane to that of the stigma, etc. Another student of mine, Mr. 

 Walter Herndon, is currently studying a species of Pleodorina, 

 with beautifully ribbed chloroplasts, between the arms of which 

 occur alternately a number of contractile vacuoles. Herbarium 

 specimens and preserved material fail to help us decide whether 

 Shaw's (1894) omission of them in his drawings was due to their 

 actual absence or to incomplete observation of his material of 

 P. californica Shaw. My point may be emphasized further per- 

 haps by two examples, one involving the author. About twenty 

 years ago as a young student he had occasion, under the gentle 

 guidance of the late M. A. Howe and T. E. Hazen, to examine 

 herbarium specimens labeled "Chlorococcum." Even under such 

 expert tutelage the specimens were not particularly convincing 

 to any of us, but with the assurance of youth the author wrote 

 (Bold, 1931) : "In cell size these specimens^ are in agreement with 

 the material I have worked widi,^ and their aggregation of angu- 

 lar cells into a loose coenobium-like mass seems to confirm the 

 identification I have made." Today he blushes at his naivete for, 

 in his subsequent experience, he has observed that almost any 

 unicellular alga, in crowded conditions, will behave in similar 

 fashion. More recently a student engaged in a survey of the algal 

 flora of a particular geographical region wrote the author as 

 follows with reference to gross, non-unialgal cultures of Chloro- 

 coccum-Xikt algae he had been studying: "The massive chloro- 

 plast is granular. 'Granular' may not be the word—, but it is not 

 a smoodi green — , uneven, almost cracked, perhaps. The pyre- 

 noid is pretty well concealed, and I believe that I have detected 

 more than one, but under the circumstances would hesitate to 

 swear whether it was a nucleus or pyrenoid." This zealous indi- 



^ Specimens of C. injusionum collected by N. L. Gardner and F. S. 

 Collins. 



2 Bold, 1 93 1. 



