376 W. A. HERDMAN. 



C and D just disappeared, tlie absorption at the ends was not greatly dimin- 

 ished. On again increasing the thickness of the layer the point of first 

 appearance of the single band was rather nearer to D than C, i. e. at X 617. 

 "The measurements obtained were as follows ; 



Stronger solution, absorption from violet end to \ 468. 

 absorption from red end to \ 716. 

 absorption between \ 630 and \ 602. 

 Solution just too weak to give any absorption between C and D gave 

 absorption from violet end to X 428. 

 absorption from red end to X 725. 

 " The colour was not affected by weak reducing or weak oxidising agents, 

 and no evidence has been obtained indicating that the pigment is of respi- 

 ratory function. It is not easily bleached; in formol solution exposure at a 

 south window for nine weeks has made no perceptible difference to its depth 

 of tint, as compared with a similar tube-full preserved during that period in a 

 dark cupboard. The localisation of the absorption points to the pigment 

 being one not hitherto met with, at least not hitherto recorded." 



Later Professor Sherrington added : 



"Haemoglobin in formol solution exhibits the spectrum of reduced hsemo- 

 globin. There is no similarity between the spectrum of the pigment here 

 examined and that of hsemoglobin. On the other hand, the position of the 

 band recalls that of the strong band given by ' bonellein,' X 643 to X 617 

 (Sorby). But bonellein was not examined in formol solution. No other 

 definite absorption baud was given by the Thalassema pigment in formol. The 

 substance is not a respiratory pigment. The spectral band-shadow sug- 



gests alliance with bonellein Of course there is no question of the 



identity of this with bonellein; the only thing the spectral map does tell 

 us is that this pigment cannot be the same as bonellein, unless — which is very 

 unlikely — bonellein has a single band in formol solution, or this a multiple 

 shadow in CS„ or CsHgO." 



Dr. Noel Paton writes to me : 



" Dr. Milne Murray and I have examined the solution after evaporating to 

 about one half and placing it in a 3-inch tube. We find a single band 

 with ill-defined edges in the red, with its centre at X 640. It was impossible 

 to fix the exact position of the edges. There is very little absorption of the 

 red end of the spectrum, which can be seen up to X 790; but there is consider- 

 able absorption of the violet end — up to about X 496. I shall send the fluid 

 back to you, unless you would like me to ask Miss Newbigin, who is working 

 at the pigments of Invertebrates, to see if it has any of the characters of a 

 lipochrome." 



I asked Dr. Noel Paton to hand the sample of fluid over to 

 Miss Newbigin, who has since sent me the following report : 



