420 MARION I. NEWBIGIN. 



as in the case of chsetopterin, the precipitate being a bright 

 green colour. The precipitate is insoluble in alcohol, and 

 after treatment with dilute acid dissolves in alcohol to form a 

 solution which contains a mixture of enterochlorophyll and 

 its one-banded acid derivative. Lead acetate affords a useful 

 test for the presence of enterochlorophyll in a solution which 

 contains so much lipochrome as to disguise the ordinary reac- 

 tions. Such a solution may be pure yellow, but with lead 

 acetate a green precipitate at once forms, the colour being in 

 striking contrast to that of the solution. 



(6) Relation to Chsetopterin. 



Enterochlorophyll is so closely related to chaetopterin that 

 the question at once arises whether or not it is identical with 

 that pigment. While leaving that question open, I may point 

 out one or two diflFerences between the two. 



First, as to the spectrum, the bands in enterochlorophyll are 

 slightly nearer the red end than those of chaetopterin, and the 

 difference appears also in the derivatives. According to Dr. 

 MacMunn, however, there is some variation in the spectrum 

 of the pigment in different animals. 



Second, as to colour, solutions of enterochlorophyll even 

 when apparently free from lipochrome pigment, do not give so 

 marked a blue on the addition of a little acid as do those of 

 chaetopterin, the colour always inclining towards green. Solu- 

 tions of enterochlorophyll in concentrated acid are of a bright 

 green colour, but the green inclines towards yellow, while 

 that of chaetopterin solutions inclines towards blue. The deri- 

 vatives show analogous differences. 



Finally, as to the solubility, enterochlorophyll seems to be 

 distinctly less soluble in dilute acid than chaetopterin. I am 

 inclined to suspect, however, that this is in part due to the 

 large amount of fat in most solutions of enterochlorophyll. 

 The differences are thus not very well marked. In relation to 

 acids, and in giving rise to a one-banded acid derivative ; in 

 the action of alkalies, and the production of a soluble alkaline 

 derivative ; in the action of salts; and in the general spectro- 



