MICRQCHEMISTRY. 105 



not yet certain, since, according to Reinke's statements, 

 this is not very probable. 



Phycocyanin is soluble in water, and in this solution has a 

 bright blue color with a red fluorescence. Its absorption- 

 spectrum shows four bands, according to Reinke. 



$. Coloring Matters of the Diatom a ceo;. 



178. The chromatophores of the Diatomacece, which are 

 colored yellowish brown in the living state, are colored 

 greenish by alkalies and dilute acids, and by concentrated 

 sulphuric acid a beautiful verdigris-green, as Naegeli has 

 shown. They contain at least two pigments, one of which 

 is surely identical with chlorophyll, while the other is often 

 called phycoxanthin, but more appropriately diatomin. 



Diatomin is characterized by being soluble in dilute 

 alcohol with a brownish-yellow color. It is not probable, 

 from the investigations already made, that it is identical 

 with carotin (cf. Askenasy I, 236 and Nebelung I, 394). 



i. Coloring Matters of the Peridinece. 



179. The Peridine& t which have recently been commonly 

 included among the Algae, are distinguished, as Klebs (V, 

 732) has shown, by the possession of true chromatophores. 

 These contain, according to Schiitt (I), three pigments, 

 which he calls Peridine-chlorophyllin, peridinin, and phyco- 

 pyrrin. Of these, Peridine-chlorophyllin is either identical 

 with, or very closely related to, chlorophyll. , 



1. Peridinin is insoluble in water, but readily dissolves in 

 alcohol, giving a fluid of the color of red wine. It is also 

 readily soluble in ether, chloroform, benzol, carbon bi- 

 sulphide, and glacial acetic acid. Its absorption-spectrum 

 shows, according to Schutt (I), the Band I of chlorophyll 

 between B and C, and is also marked by a strong absorp- 

 tion in the green-yellow. 



2. Phycopyrrin (from Ttvppos, red-brown) is soluble in 

 water, giving a dark brown-red fluid. It is also easily 

 -soluble in alcohol, ether, bisulphide of carbon, and benzol. 



