CHAP. VIII.] EPITHELIAL TISSUES, &C. 307 



Mollusca. Aplysio-purpurin from Aplysia * and Doris. 



Janthinin in Janthina. 

 Tyrian purple 2 in several species of Murex and 



Purpura. 



Other pigments yielding no bands. 



Vertebrata. In addition to colouring matters referred to in other 



parts of this book a bluish-green pigment with 

 a single band, extending from B to beyond 0, 

 destroyed by heat, acids and alkalies ; found in 

 Odax, 3 spp. and in Labrichthys Richardsonii 3 . 



A short account of the chief characters of certain of the above- 

 named colouring matters will now be given. 



Blue Stentorin 4 . 



This blue colouring matter obtained from Stentor coeruleus is 

 characterized by a spectrum with two absorption bands ; of these the 

 darker is on the red side of C; a second lighter band, between 

 D and E, occupies approximately the space intervening between the 

 middle of the a band of oxy-haemoglobin and the /3 band of the same 

 body. The colour is unaffected by acetic, hydrochloric, and sulphuric 

 acids; caustic potash causes the colour to become darker, the band 

 between D and E disappears, and that between B and C becomes 

 darker and is shifted somewhat nearer towards B. 



Actiniochrome 5 . 



This is a red colouring matter obtained by Moseley from 

 some specimens of Bunodes crassicornis. It possesses an absorption 

 band having approximately the position of the band a of oxy- 

 haemoglobin. 



Bonellein*. 



This is a colouring matter obtained by Sorby from Bonellia 

 viridis. According to Sorby it resembles blue chlorophyll in many 

 respects, but differs in only being temporarily altered by acids, the 

 original colour returning on neutralization. It occurs in fine granules 

 in the epidermal protoplasm, and is insoluble in water, soluble in 

 alcohol, ether and carbon disulphide. The following are the wave- 

 lengths of the centres of the absorption bands of Bonellein (expressed 

 in millionths of a millimetre) : 



1. Alcohol solutions, alkaline or neutral 

 662, 636, 611, 587, 520, 490. 



1 An Italian chemist has asserted that an aniline base is present in Aplysia, 

 (Moseley, op. cit., p. 13). 



2 Lacaze-Duthiers, "Memoire sur la Pourpre," Annales des Sciences Naturelles, ZooL 

 Ser. iv., Vol. xn. pp. 584. 



3 George Francis, Nature, Vol. xn. p. 167. 



4 Lankester, Op. cit., (see foot-note to p. 305). 

 3 Moseley, Op. cit., (see foot-note to p. 305). 



6 Sorby, Op. cit. 



202 



