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THE AMERICAN NATURALIST [Vol. XLV 



Other examples of this chemistry are numerous, but I 

 can only mention one or two. Tower states (1903, p. 

 54) "Sundwick and Ledderhose conclude that chitin is 

 an amido derivative of a carbohydrate having the for- 

 mula C r> H 100 50 ." 4 I was willing to allow this as an error 

 in proof-reading had not the same C e H 100 O 30 occurred 

 again on page 55, where he adds "and hence glucoside, 

 like cellulose? and other plant substances." 



Again I quote from the 1906 paper (p. 123) "Griffiths 

 farther isolates and studies a green pigment which is 

 allied to uric acid or is a uric acid derivative called lepi- 

 dopteric acid (C n H 10 Az 2 N8O 10 ?)." I have not seen 

 Griffiths »s paper (1892), but, from the formula which 

 Tower gives, I would say that the question mark is well 

 placed, inasmuch as the English form of nitrogen is not 

 known to differ from the French variety. Some of the 

 other errors will be referred to in connection with my 

 work. 



Experimental, 

 The Formation of the Figment bp Oxidation. — The 

 material employed was the pupae and adults of the Col- 

 orado potato beetle, Leptinotarsa decemlineata Say. 

 Large larvae were secured in the field and placed in bat- 

 tery jars, provided with abundance of fresh potato stalks, 

 and containing about four inches of sifted soil in the 

 bottom. The top of the jar was covered with mosquito 

 netting. Within a few days all of the larvae had entered 

 the soil and had pupated. When the adult beetles emerge 

 from the pupal skin, the elytra are an almost uniform 

 light yellow color, and upon this surface the lines of the 

 darker color pattern shortly appear. In accordance 

 with my former work I have found that this pigmenta- 

 tion is an oxidation, induced by an oxidase of the tyro- 

 sinase type. 



Tower (1903, p. 58) states that he tested the rate of 

 pigmentation when the pupae were kept in an atmosphere 



4 My italics. 



