8G METHODS OF PREPARING OXY-HAEMOGLOBIN. [BOOK I. 



II. A platinum capsule is placed in a freezing mixture and then 

 freshly defibrinated blood is poured into it, so as to convert it into a red 

 lump of ice. After being in this freezing mixture for half an hour, the 

 blood is allowed to thaw gradually, and the contents of the basin are then 

 poured into a glass vessel of such dimensions that the bottom is covered by 

 the lake-coloured blood to a depth of 1 5 millimetres ; the glass vessel is 

 then set aside in a cool place. In a short time the blood of guinea-pigs and 

 of squirrels furnishes by this method well-formed crystals. According to 

 Rollett, cat's blood is next in the order of facility of crystallization. Then 

 follow dog's blood, human blood, and the blood of rabbits. The blood 

 of the pig and of the frog yield by this method no crystals, though their 

 oxy-haemoglobin is crystallizable. In order to obtain crystals from the 

 blood of these animals, the process of freezing and thawing must be fre- 

 quently repeated \ 



This method is, accord ing to Preyer, very convenient in winter, especially 

 when comparative crystallographic and optical investigations of the oxy- 

 haemoglobin of the blood of many different animals have to be carried on. 



III. In this method, the stroma of the coloured corpuscles is dissolved 

 by the addition to the blood corpuscles of a watery solution of crystallized 

 bile (a mixture of sodium glycocholate and taurocholate). 



A. The blood of the horse is collected in a cylinder and at once 

 cooled. As soon as the plasma and subjacent stratum of colourless cor- 

 puscles have separated, these are separated from the red corpuscles, and the 

 mass of residual red corpuscles is treated with a 0*5 per cent, watery 

 solution of crystallized bile. Then the mixture is allowed to coagulate. 

 The fibrin as it separates encloses the yet undissolved corpuscles, so that the 

 surrounding deeply lake-coloured fluid is entirely free from them. To the 

 fluid, which is kept continually stirred, there is then added 90 p.c. alcohol 

 containing a trace of acetic acid, as long as the precipitate which is pro- 

 duced continues to redissolve. After some hours the fluid is converted into 

 a magma of crystals which are collected on a filter and washed, first with 

 diluted alcohol and then with iced water. Instead of this method we 

 may use : 



B. 100 c.c. of dog's blood is allowed to coagulate in a shallow basin ; the 

 clot is then separated from the sides of the vessel and set aside for 24 hours. 

 (The centrifugal apparatus might be used with advantage.) The serum 

 is then decanted and the clot washed with water; it is then finely 

 divided and diffused by the help of a syringe through 50 c.c. of water, and 

 after standing for 24 hours is filtered through linen and the residual fibrin 

 washed with 10 c.c. of water. The mixture thus obtained of diluted serum 

 and blood corpuscles is treated with 2 c.c. of a syrupy solution made by 

 dissolving 1 part of crystallized bile in 3 parts of water ; after 24 hours 

 every blood corpuscle has disappeared. Nevertheless the fluid filters 

 very slowly. On adding 20 c.c. of 90 p.c. alcohol for every 100 c.c. of the 

 nitrate, the latter is converted into a magma of crystals which are washed 

 first in dilute alcohol and then in iced water. 



1 Rollett, "Versuche und Beobachtungen am Blute." Sitzungsber. d. math, 

 naturw. Classe der kaiser. Akad. d. Wissenschaft. Vol. XLVI. (1863). Abth. n., p. 77. 



