SINCE PREYER'S INVESTIGATIONS. 121 



From cat's blood, Donogany states, oxyhemoglobin crystals can be 

 obtained by any of the usual methods except the methods of Gscheidlen, 

 Rollett, and Wedl, by which only reduced hemoglobin can be produced. 

 From horse's blood good results were recorded with Canada balsam, damar 

 varnish, chloroform, amyl alcohol, pental, xylol, colophonium dissolved in 

 amyl alcohol, pyrogallic acid, or by freezing. The crystals are doubly 

 refracting, and they consist for the most part of oxyhemoglobin. With the 

 methods of Gscheidlen and Wedl, crystals of reduced hemoglobin were 

 obtained. If the Rollett method is used, combined with distilled water, 

 a mass of reduced-hemoglobin and oxyhemoglobin crystals is formed. 

 The blood of pigs, which is looked upon as crystallizing with difficulty, he 

 found crystallized readily by the use of ethereal oils. The formation of 

 crystals went on slowly, and the crystals were large and well developed. 

 The crystals were doubly refracting and consisted of oxyhemoglobin. 



From the blood of white mice crystals could not be produced by the aid 

 of Canada balsam, distilled water, chloroform, ether, alcohol, or xylol. Ox 

 blood did not crystallize by treatment with Canada balsam, damar varnish, 

 ether, amyl alcohol, xylol, chloroform, pental, ethereal oils, or pyrogallic 

 acid. By freezing and by Gscheidlen's method, combined with Canada 

 balsam or damar varnish, only small needles could be obtained. From 

 their light color, Donogany believes that they were probably oxyhemo- 

 globin. They were doubly refracting. The coloring matter of the blood of 

 rabbits also crystallized with difficulty. The addition of ether, Canada 

 balsam, chloroform, pental, ethereal oils, and acetone gave negative results. 

 With the method of Gscheidlen and with damar varnish, only small needles 

 could be obtained. With Rollett's method rather large needles were formed. 

 The best result was obtained with pyrogallic acid. The crystals formed, 

 he states, consisted of reduced hemoglobin. The blood of the duck treated 

 with damar varnish, xylol, ether, amyl alcohol, Canada balsam, chloroform, 

 colophonium solution, distilled water, and by quick cooling, scarcely 

 yielded crystals, and even in the most favorable instance only stunted ones. 

 Gscheidlen's method, he writes, can be used with much better results, 

 although here, too, crystallization goes on slowly. The crystals were purple- 

 red, almost blue, needles or prisms, and consisted of reduced hemoglobin. 

 Later these crystals, under the influence of atmospheric air, changed to 

 flesh-colored rhombic, even 6-cornered tablets, which were doubly refract- 

 ing, and consisted, perhaps, of oxyhemoglobin. 



From guinea-pig blood Donogany produced crystals by means of 

 Canada balsam. They formed quickly, and also became quite large if the 

 Canada balsam used was not very thin and the preparation stood in a cool 

 place. If form and size are not important good results can be obtained, he 

 states, by means of ethylidene chloride. With damar varnish crystallization 

 goes on somewhat slowly and at the sacrifice of sharp edges. Pyrogallic 

 acid and valerian oil did not cause crystallization. Ether, chloroform, 

 xylol, amyl alcohol, acetone, Canada balsam dissolved in xylol, freezing, a 

 mixture of water and alcohol, and repeated treatment with Canada bal- 

 sam gave only poor results. With ethyl bromide, after the course of an 



