156 PHYSIOLOGY OF THE INVERTEBRATA. 



its spectrum is represented in Fig. 30, c. The band before D 

 was from X 620.5 to X 593, the second about X 583.5 to X 572, 

 the third uncertain (about X 551 to X 532). After the addi- 

 tion of ammonium sulphide, " the only band seen with cer- 

 tainty was that before D, which seemed slightly nearer the 

 violet." In an alcoholic solution only a faint band was visible 

 from about X 501 to X 477. 



In a specimen in which the blood appeared a bright 

 carmine-red colour, MacMunn obtained the spectrum repre- 

 sented in Fig. 30,/. The second band of this spectrum 

 resembles the first band of hgemochromogen, and is really 

 the same as Fig. 30, h. 



Fig. 30,^ represents the spectrum of the blood from a 

 dilated part of the principal blood-vessel of Scrpula. " The 

 darkness of the second band at once distinguishes the pigment 

 from chlorocrurorin." Fig. 30, h and i also represent the spectra 

 of the blood from the same part of a third and fourth specimen. 



" An aqueous solution of blood obtained from a dozen 

 specimens, whose blood gave the above spectra, was yellow, 

 and showed the three bands represented in Fig. 30. y, and these 

 gave the following readings: — First band, X618 to X 593 • 

 second, X 582 to X 570.5 ; third, X551 to X 529.5 (?) On 

 treatment with sulphide of ammonium the solution became 

 slightly greener ; no bands could then be seen after D, and 

 that before it was very faint. Hence it would appear that the 

 two- and three-banded spectrum denotes the oxidised state. 



" In some Snjmlce, whose blood was not red but brown, 

 the bands before and after D reminded one of chlorocruoriu 

 (Fig. 30, k). An aqueous solution of the blood of these speci- 

 mens had a reddish tint by gaslight, and gave three bands, 

 which read as follows: — First, X 620.5 to X 595 ; second, 

 X 538.5 to X 570.5 ; third, X 551 to X 532. On adding sul- 

 phide of ammonium, the band before D read X 620.5 to 

 X 598, and a second band was visible after D, which could not 

 be measured. On adding to this reduced fluid some caustic 

 soda, at first the only change produced was the disappearance 



