SINCE PREYER'S INVESTIGATIONS. 127 



corpuscles, 2 volumes; and to cat's corpuscles, 1 volume. On the addition 

 of alcohol in the cold, etc., according to the Hoppe-Seyler method, and twice 

 recrystallization, he obtained, he states, absolutely pure crystals. His 

 elementary analysis of cat oxyhemoglobin will be found on page 71. 



The very simple and satisfactory "Canada balsam" method of von 

 Stein (loc. cit.) for preparing small quantities of crystals from readily 

 crystallizable bloods was again used by Mm in a later research (Archiv f. 

 path. Anat. u. Phys., 1900, CLXII, 477) in a determination of the effects of 

 certain reagents on crystallization of guinea-pig's blood. The addition of 

 sodium chloride up to 2 per cent aided crystallization, while quantities 

 beyond this hindered; calcium chloride, sulphureted hydrogen, and nitrous 

 oxide hindered crystallization. Von Stein also noted variations in crystalline 

 form from the typical tetrahedra to forms ranging from truncated tetra- 

 hedra to 6-sided plates. 



A painstaking study of the crystallography of the crystals of pigeon's 

 blood was made by Schwantke (Zeit. f. physiolog. Chemie, 1900, xxix, 

 486). His results will be referred to fully in subsequent chapters. 



A new method of getting rid of the stromata, which whether in sus- 

 pension or in solution hinder the crystallization of hemoglobin, was devised 

 by Schuurmanns-Stekhoven (Zeit. f. physiolog. Chemie, 1901, xxxin, 296). 

 The blood corpuscles are washed with 1 per cent salt solution by centri- 

 fugalization, and then shaken violently for 2 hours with asbestos wool. 

 The blood-coloring matter passes into solution, while the stromata for 

 the most part cling to the asbestos and are removed by nitration. By 

 this method the hemoglobin is not brought in contact with ether. 



The hemoglobin solution is placed in a parchment-paper dialyzer, 

 which is suspended in 45 per cent alcohol, and put in an ice-chest. As 

 soon as crystals begin to form on the wall of the dialyzer (after 24 to 

 48 hours) the contents of the dialyzer are placed in a cylindrical vessel 

 and then set in an ice-chest until crystallization has been completed. 

 The hemoglobin is not brought in contact with any more alcohol than is 

 necessary for the crystallization. The crystal pulp is as far as possible freed 

 by pressure from the mother-liquor, after which the crystals are dissolved 

 in the smallest possible amount of water at 37. This solution is again dis- 

 solved and placed in the dialyzer in 45 per cent alcohol. Crystallization 

 begins much more quickly than the first time. After crystallization has 

 been completed the crystals are separated from the mother-liquor and dried, 

 first on porous plates and then in a porcelain bowl over chloride of calcium 

 at room temperature. 



In the monographs by Schulz (Krystallization von Eiweisstoffen und 

 ihre Bedeutung fur die Eiweisschemie, Jena, 1901) and Robert (loc. cit.) 

 much of the literature on the processes for preparing crystals of hemoglobin 

 is referred to. The latter gives an account of blood crystals which he pre- 

 pared from various species, and he attempts the support of the hypothesis 

 of Hoppe-Seyler regarding the existence of the blood-coloring matter in the 

 form of "arterin" and "phlebin." 



Stewart (American Journal of Physiology, 1903, vm, 102), in his 

 studies of the actions of laking agents on the blood, found that intraglobular 



