42 



HEMOGLOBIN 



The question naturally arises : Do the above figures indicate a true 

 specificity, or do they merely signify mixtures of two or three kinds 

 of haemoglobin in various proportions? 



In order to gain some light on this subject samples of haemoglobin 

 of different spectroscopic constants were partially crystallised (7). It 

 might be supposed that one or other fraction would crystallise out, 

 leaving the rest in the solution, and that, therefore, the residual 

 solution and the redissolved crystals would differ spectroscopically 

 both from the original solution and from one another. The following 

 table gives the "span," i.e. the distance between the a-bands for 

 oxy- and CO -haemoglobin of various animals before crystallisation 

 and after resolution of the crystals : 



Two interesting cases may be cited, in each of which a couple of 

 specific haemoglobins may be found within the same animal. The first 

 was carried, out by my friend Mr Charles Stockman (7). A leech was 

 starved until its alimentary canal was presumed to be free from 

 blood. It was then given a meal of that material at my own expense, 

 and ten days later it was examined. The blood in the alimentary 

 canal was considerable in amount and was indistinguishable from that 

 in my own vessels ; that from the vessels of the leech itself was quite 

 different from either. This was done in the case of two separate leeches. 



The second case is more interesting in many ways, one of which 

 is that it has been so productive of future research, being the starting- 

 point of Keilin's(7) researches. The larva of the bot-fly grows within 

 the horse. Its life-history is as follows. The eggs are found on the 

 hair of the horse above the hoof. The horse licks the hair and 

 so ingests the larvae, which develop in his stomach wall. There the 

 larvae attain the size of acorns, and within them is found a con- 

 siderable quantity of haemoglobin. This haemoglobin is clearly all 

 manufactured within the horse, but it is quite different from equine 

 haemoglobin, the bands being nearer to the red in the Gastrophilus 

 larva, and the span shorter. f 



