igii] Carl L. Aisberg 109 



Knowing the energy value of the cellulose — 4.220 Cal. — and 

 that of the proclucts of the fermentation, it may be computed that 

 1.048 Cal. of energy are Hberated as "heat of fermentation" in the 

 fermentation of one gram of cellulose. Expressed in terms of 

 methane, 1.1549 Cal. of energy are lost as "heat of fermentation," 

 for every Cal. of methane excreted by the animal. 



Applying this factor to results of experiments lipon steers with 

 the respiration calorimeter, in which the amount of methane ex- 

 creted and the amount of heat emitted after the Ingestion of a 

 known amount of food were determined, it is found that in the 

 case of a hay ration, 36.8 per cent. of the "heat of digestion " arose 

 from the methane fennentation. On the hay ration 32 per cent. 

 of the "heat of digestion" arose from the methane fermentation 

 of the carbohydrates. 



The Pigmentation of the Adult Periodical Cicada, with a Note 



on Chemical Anti-Oxidases 



ROSS AIKEN GORTNER 



(The Station for Experimental Evolution, Carnegie Institution of 

 Washington, Cold Spring Harbor, L. I. ) 



The black pigment of the periodical cicada ( Tibicen septendecim 

 L, ) is shown to be produced by the interaction of a chromogen and 

 an oxidase of the tyrosinase group. Coloration proceeds after 

 death but does not produce the normal uniform coloration, since, 

 apparently, the tyrosinase is secreted together with the new cuticula, 

 and after death this secretion ceases. 



In the note on chemical anti-oxidases the Suggestion is made 

 that, perhaps, dominant whites are due to the presence of aromatic 

 Compounds carrying two hydroxyl groups in meta position to each 

 other. It was noted that tyrosin did not produce the typical colora- 

 tion in the presence of tyrosinase when orcin, resorcin, or phloro- 

 glucin — all meta-di-hydroxyl benzol derivatives — were present in 

 the Solution. This result was, apparently, caused by the tyrosinase 

 being affected in the same manner as though an anti-oxidase were 

 present, for proof was given that the tyrosin had not united chemic- 



