INTEGUMENT. 27 



" quite black," aud during metamorphosis assume the 

 light yellowish-grey gromid colour through the greater 

 part of the pigment-cells turning pale. A more 

 glai'ing misrepresentation could not be imagined. 

 Far from being black, the tadpole of Pelobates fuseus 

 is normally pale brown, with dai^ker spots and marb- 

 lings, as may bo seen from the figure in this work. 

 And the tadpole of Pelobates caltripes, a species which 

 has the same dark spots as P.fuscus after transfor- 

 mation, is usually very pale reddish yellow. A proof 

 that the yellow and red pigments are chemically dis- 

 tinct from the brown or black is to be found in the 

 different action of alcohol on them. Thus yellow 

 pigment is rapidly destroyed; therefore green frogs 

 turn olive or blue in spirit. Certain crimson pig- 

 ments, not unfrequent in frogs, resist the action of 

 alcohol and light better than the brown, which by dis- 

 coloration may turn to reddish brown or rufous, these 

 two reds strongly contrasting in specimens that have 

 long been in spirit, Tornier goes even so far as to doubt 

 the presence of any but the brown pigment in reptiles ; 

 surely the green of certain tree-snakes of the genera 

 Dryophis and Laches is , which colour the spirit in which 

 they are preserved to the extent of resembling green 

 Chartreuse, is due to the presence of a chemically 

 distinct colouring matter, and has no relation whatever 

 to the green of frogs, which, produced, as we have seen, 

 by a combination of black and yellow, disappears in 

 spirit when the latter pigment is destroyed. 



Another instance of the same author's carelessness 

 in the selection of examples is to be found a little 

 further in the same work (p. 130), where he declares 

 that Batrachian larvae whicb develop in the light are, 

 with few exceptions, uniformly dark, or more usually 

 deep black, and retain that coloration until close to 

 the metamorphosis. I believe the exception is just 

 the other way. The embryos of Bomhinator and 

 Alytes are yellowish or pale brown striped with 

 blackish, those of iZ^/^a uniform yellowish, those oi liana 



