ALBUMINS OR PROTEINS. 123 



with normal crystals. Such products have also been observed in animal 

 tissues. Thus, six-sided plates have been noticed in the intestinal 

 epithelium of the meal-worm, Tenebrio molitor. 1 R. List 2 states that 

 he has observed rhombohedrons and hexahedrons in the pigment cells of 

 the radial nerves of Sphcerechinus granularas, which gave the albumin 

 reactions. The small yolk plates, as well as other rectangular and quad- 

 rangular plates obtained from the eggs of fishes and amphibora, also be- 

 long to this class. Such products have also been observed in the eggs of 

 the roe 8 as well as in the epithelium of the testes in man. 4 



These discoveries do not lead to any decision regarding the crystalline 

 qualities of the albumins. The fact that some of the products observed 

 gave albumin reactions does not prove that they were albumins. Small 

 impurities of albumin might have caused them. We would be but little 

 benefited even if the fact should be established that these crystalline 

 substances were albumins. The only value of crystals lies in possibility 

 of recrystallization and purification. 



As a matter of fact it has been found possible not only to obtain many 

 of the albumins in crystalline form but many of them have also been re- 

 crystallized. Maschke 5 was the first to interest himself in this direction. By 

 evaporating a saturated solution of Bertholletia (Brazil nuts), he ob- 

 tained aleuron crystals in six-sided, tabular prisms. 



Schmiedeberg 6 continued this work. The protein crystals were isolated 

 from the Brazil nuts by washing them out with petroleum ether. They 

 were then dissolved in distilled water at 30-35 degrees, and precipitated 

 by passing carbon dioxide into the solution. The precipitate was re- 

 dissolved by treating it with an excess of magnesium oxide at 30-35 

 degrees. By careful concentrating the solution, small crystals, of the 

 size of poppy seeds, settled out. These contained 1.4 per cent MgO. 

 Drechsel 7 improved this method considerably. Instead of evaporating he 

 removed the water by dialysis with absolute alcohol. 



After grinding a large number of seeds and removing the fat, octahe- 

 dral crystals have been obtained by means of a five per cent salt solution 

 at 60 degrees. They can be redissolved and again precipitated. Such 

 crystals were obtained from cotton seed, hemp seed, and sun-flower 

 seeds. 



1 J. Frentzel: Arch. mik. Anat. 26, 287; Berl. entomol. Zeit. 26, 1882. W. Bieder- 

 mann: Pfliiger's Arch. 72, 105 (1898). 



2 R. List: Anat. Anzeiger, 7, 185 (1897). 



V. v. Ebner: Sitzungsber. Akad. Wissensch. zu Wien. 110, part 3 (1901). 



Lubarsch: Virchow's Arch. 145, 317 and 362 (1896). 



O. Maschke: J. prakt. Chem. 74, 436 (1858). 



O. Schmiedeberg: Z. physiol. Chem. 1, 205 (1877). 



E. Drechsel: J. prakt. Chem. 19, 331 (1879). 



