152 PLANKTON OF WISCONSIN LAKES 



little below the mean of the blue-green algae, but the percentages of 

 ether extract and of crude fiber are appreciably higher than in the 

 latter. Only one sample of the blue-greens has a smaller percentage of 

 nitrogen free extract than Ankistrodesmus and only one has a smaller 

 percentage of pentosans. 



On July 6, 1916, an abundant growth of the flagellate Volvox was 

 found in Lake Monona and enough of this material was secured for a 

 chemical analysis. This flagellate yielded a smaller amount of nitrogen 

 than the blue-green algae; still the percentage of nitrogen is large 

 enough to show that almost half of the dry material consists of crude 

 protein. The percentages of ether extract and of crude fiber are some- 

 what larger in this Volvox material than the average for the blue-green 

 algae, with the exception of the crude fiber in Lyngbya. The pentosans 

 are smaller in Volvox than in the blue-greens, while the nitrogen free 

 extract is about the same as the average for the latter group. 



All of the percentages for Volvox are somewhat smaller than those 

 for Ankistrodesmus except that of nitrogen free extract. (Table 49, 

 p. 215.) 



Brandt* records the results of a chemical analysis of some marine 

 flagellates; his sample consisted of peridinians, chiefly the flagellate 

 Ceratium. The crude protein in this material amounted to 12.68 per 

 cent of the dry weight of the sample, the fat or ether extract 1.3 per 

 cent, the crude fiber 41.5 per cent, the nitrogen free extract 39.0 per 

 cent, and the ash 5.2 per cent. (Table 51.) A comparison shows that 

 the percentage of crude protein in the sample of Volvox from Lake 

 Monona is more than three times as large as that in the above sample of 

 marine peridinians, while the percentage of ether extract is more than 

 four times as large in the former as in the latter. The crude fiber in 

 the peridinians is more than six times as large as that in Volvox and the 

 nitrogen free extract is somewhat larger in the former ; the percentage 

 of ash is a little larger in Volvox than in the peridinians. 



The two samples of green algae which do not belong to the regular 

 plankton forms, namely Spirogyra and Cladophora, yielded different 

 results from those obtained on the blue-green algae and also from 

 those of the two green algae noted above. The percentage of nitrogen 

 is less than half as large as the mean of the blue-greens and also less 

 than half as large as the percentages in Ankistrodesmus and Volvox; 

 this means correspondingly low percentages of crude protein in the 

 two filamentous algae. Whipple and Jackson^ found 4.5 per cent of 

 nitrogen in the sample of Spirogyra which they analyzed. (Table 51.) 



'Wissenseh. Meeresuntersuch., Abt. Kiel, N. F., Bd. 3, 1898, p. 88. 

 'Jour. N. E. Waterworks Assoc, Vol. 14, 1899, pp. 1-25. 



