ANALYSIS OF OEGANISMS 167 



The five samples of copepocls listed in table 49 contained a relatively 

 small percentage of ash and similar results have been obtained in more 

 than forty other ash determinations on small samples of Diaptomus, 

 Cyclops, Epischura, and Limnocalanns. A sample from Spring Lake, 

 Wisconsin, containing Diaptomus yielded 17.07 per cent of ash and 

 another from Silver Lake containing Cyclops gave 12.04 per cent of ash. 

 These two samples of copepods are the only ones obtained from Wis- 

 consin lakes which have contained more than 9.0 per cent of ash and 

 the majority of them have yielded less than 6.0 per cent. Specimens of 

 Cyclops 8 from Lake Okoboji, Iowa, gave 10.0 per cent of ash, while 

 samples of Cyclops and of Diaptomus from some of the Finger lakes 

 and from Lake George, New York, contained from 11.49 per cent to 

 15.38 per cent of ash. 



Volk 9 records an analysis of another copepod, namely, Eurytemora. 

 He states that 78.48 per cent of the dry weight of the material consisted 

 of muscle and other tissue, 6.2 per cent fat, 11.08 per cent chitin, and 

 4.24 per cent ash. (See table 51.) Apparently he determined the 

 ether extract, crude fiber, and ash, and then called the remainder 

 " muscle and other tissue." The percentage of ether extract or fat is 

 much smaller in Eurytemora than in the five samples of Wisconsin cope- 

 pods, but the percentage of crude fiber or chitin is larger in the former ; 

 the percentage of ash in Eurytemora is substantially the same as that 

 of Limnocalanus. 



Brandt 10 gives an analysis of a sample of freshwater copepods; his 

 material yielded 57.25 per cent of crude protein, 6.01 per cent of ether 

 extract or fat, 4.54 per cent of crude fiber or chitin, and 9.21 per cent 

 of ash. (See table 51.) A comparison of his results with those obtained 

 for the samples of copepod material collected in Wisconsin lakes, shows 

 that two of the latter yielded a smaller percentage of crude protein 

 and three a larger percentage; four of the latter contained a larger 

 percentage of chitin or crude fiber and all five gave a larger percentage 

 of fat or ether extract. The percentage of ether extract shown for 

 Limnocalanus is more than six times as large as that in Brandt's ma- 

 terial. The percentage of ash recorded by Brandt is larger than that 

 in the five copepod samples shown in table 49. The nitrogen free ex- 

 tract in his sample of freshwater copepods amounted to 22.99 per cent 

 of the dry weight ; this is nearly twice as large as the maximum per- 

 centage of nitrogen free extract in the five samples of Wisconsin cope- 

 pods and five times as large as the minimum. 



8 Birge and Juday, Univ. of Iowa Studies in Nat. Hist., Vol. 9, 1920, pp. 1-56. 



9 Verhand. d. Naturwis. Vereins in Hamburg, 3. Folge XV, 1907, p. 45. 



10 Wissensch. Meeresuntersueh., Abt. Kiel, N. F., Bd. 3, 1898, p. 71. 



