124 LECTURE VII. 



It is a matter of great importance that albuminous bodies have been 

 crystallized which do not exist in the crystalline form in nature. 

 Hofmeister * succeeded in crystallizing egg-albumin by treating a given 

 volume of egg-white with an equal volume of a cold, saturated solution of 

 ammonium sulphate. The precipitate consisted of globulins, while the 

 solution contained the albumins. By concentrating the nitrate from the 

 globulins at the usual temperature, beautiful microscopic needles were 

 obtained, which could be redissolved in a dilute ammonium' sulphate 

 solution, and obtained again by evaporation. The precipitation of these 

 crystals can be greatly accelerated by making the solution faintly acid, 

 by adding either dilute acetic, sulphuric, or hydrochloric acids. 2 Serum 

 albumin has been crystallized in the same manner. 3 Albumin from 

 horse-blood serum has also been obtained in crystalline form. We will 

 mention the fact here, that other albuminous substances are said to 

 have been crystallized, such as casein, lactalbumin, etc. We do not 

 need to dwell longer on this subject, for the investigations are not very 

 convincing. 



We are acquainted with a protein which has itself not yet been obtained 

 in crystalline form, although one of its compounds which occurs in nature 

 can be crystallized easily. We refer to the coloring matter of the blood, 

 which is a compound of the albumin globin, and another substance, 

 hematin, which is not of an albuminous nature. Hiinefeld 4 noticed a 

 crystalline separation when blood was dried between two glass plates. 

 Reichert, 5 however, is credited with being the true discoverer of oxy- 

 hemoglobin crystals. He observed them on the placenta of a nearly 

 mature guinea-pig foetus and also on the mucous membrane of the uterus 

 of the mother. Oxyhemoglobin may be prepared in various ways. The 

 most satisfactory method consists in centrifugalizing defibrinated horse- 

 blood, pouring off the serum, and washing the paste of blood corpus- 

 cles with isotonic salt solution until perfectly freed from serum. The 

 blood corpuscles are mixed with 2-3 times their volume of water at 

 30-35 degrees and the solution strained. In order to remove the stro- 

 mata of blood corpuscles, the solution is cooled to degrees, shaken with 

 ether and one-quarter of the total volume of absolute alcohol, also at 



1 F. Hofmeister: Z. physiol. Chem. 14, 165 (1889); 16, 187 (1891). 

 3 F. G. Hopkins and S. N. Pinkus: J. Physiol. 23, 130 (1898). H. T. Krieger: 

 Diss. Strassburg, 1899. 



3 A. Giirber: Sitzungsber. physikal-med. Gesellsch. zu Wiirzburg, 1894, 143. A. 

 Michel: Verhandl. d. physikal-med. Gesel. zu Wiirzburg, 29, 28, No. 3 (1895), and Diss, 

 Wiirzburg, 1895. 



4 F. L. Hiinefeld: Der Chemismus in der tierischen Oxidation, F. A. Brockhaus, 

 Leipzig, 1840. 



s B. Reichert: Arch. Anat. Physiol. 1849, p. 197; 1852, p. 71. Cf. Fr. N. Schulz: 

 loc. cit. p. 23. 



