64 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 



spirographidin and spirographin from the skeletal tissues of the worm Spiro- 

 graphis. Krukenberg obtained a hyalogeri also from the tubes of Onupliis 

 tubicola, another from the membrane of Descemet and lens capsule (membranin, 

 C. T. Morner), 1 and another from hyaline cartilage (now called chondroitin- 

 sulphuric acid, see " Cartilage "). These substances are all, like the mucins and 

 mucoids, decomposed by acids with the formation of a reducing substance. 

 They differ from the mucins in some of their solubilities, but it is doubtful 

 whether they should be classed apart from the mucoids. 



Phospho-yluco-proteids. These substances not only yield a reducing 

 carbohydrate or carbohydrate-like body, like the mucins and mucoids, but on 

 gastric digestion they leave a residue of pseudo-nuclein, a substance which, 

 like nuclein, contains phosphorus. Pseudo-nuclein does not, however, yield 

 bodies of the xanthine group, on further decomposition, as do true nucleins. 

 Among these substances are the following : 



(a) IchthuHn, a substance separated from the eggs of the carp by Walter, 8 

 and at first supposed to be identical with vitellin. 



(b) Helico-proteid, secreted by the glands of the snail (Helix poinatia), and 

 separated by Hammarsten. 3 By the action of alkalis a levorotatory carbohydrate 

 (animal sinistrin) is split off ; a dextrorotatory reducing sugar is obtained by the 

 use of dilute mineral acids. 



(c) The principal constituent of the cells of the pancreas is a complex 

 nucleo-proteid which Hammarsten 4 considers to be identical with trypsin ; 

 by boiling this, it is split into coagulated proteid and a phospho-gluco-proteid. 

 The sugar which this substance gives, on treatment with dilute acids, is 

 probably a pentose (see p. 3). 



Kossel and his pupils have also obtained reducing sugar-like substances 

 from yeast nuclein. 



In concluding the subject of the gluco-proteids, it may again be mentioned 

 that Pavy regards all the common proteids (casein excepted) as having a 

 glucoside constitution (see p. 30). Whether this be so or not, the fact insisted 

 upon by Pavy that a carbohydrate may be obtained by hydrolytic decompo- 

 sition of proteids has been confirmed by other observers. Thus K. Morner 

 obtained from serum globulin a reducing substance on treatment with 

 hydrochloric acid, which, like Pavy's, is optically inactive ; but failed to get 

 such a substance from purified myosin, vitellin, crystallin, serum albumin, and 

 egg albumin. He got it from fibrin, but considered that it was due to carbo- 

 hydrate in entangled blood corpuscles. 5 I myself was at one time of opinion 

 that Pavy's results, which were principally obtained with egg-white, were due 

 to the admixture of the pure albumin with a mucoid (ovomucoid, which 

 exists to the extent of 10 per cent, in egg-white) ; but I learn from Dr. Pavy 

 that his method of preparing coagulated egg-white would exclude any large 

 admixture of this kind. Pavy's work, moreover, has been recently confirmed 

 by N. Krawkow. 6 He found egg-white difficult to obtain free from ovomucoid, 

 but the purest products he obtained always yielded a reducing substance, 

 which gave a crystalline osazone (melting at 183 to 185 C. ; Pavy gives 

 189 C.). This reducing substance he regards as a carbohydrate, though he 

 does not commit himself as to its identity. He, however, never found pen- 

 toses, nor did he find that the gastric digestion of egg albumin yielded any 

 carbohydrate. The same carbohydrate was obtained from acid albumin, 

 alkali albumin, albumose, peptone, fibrin, serum albumin, serum globulin, 

 and lact-albumin. Casein, vitellin, gelatin, and nucleo-proteid from peas 

 gave a negative result. Albumin from peas yielded an osazone rather 



1 Ztsclir.f. physiol. Chem., Strassburg, Bd. xviii. S. 213. 2 Ibid. Bd. xv. 



3 Arch.f. d. ges. Physiol., Bonn, Bd. xxxvi. 



4 Ztschr. f. physiol. Chem., Strassburg, Bd. xix. S. 19. 



5 CentralU.f. Physiol., Leipzig, Bd. vii. S. 581. 



6 Arch.f. d. ges. Physiol., Bonn, 1896, Bd. Ixv. S. 281. 



