460 THE ALBUMINOID BODIES. 



constituents of the cell-body, and accordingly they are widely distributed in the 

 animal and vegetable kingdoms. The nucleins have a strongly acid character. 

 They are divided into the following two groups : 



1. Paranucleins, which consist of albumin plus phosphoric acid. If more 

 albumin is added to paranuclein, nucleoalbumin is formed. Casein is such a 

 body, in which, besides, calcium, is present for the neutralization of the acid. It 

 occurs in solution in the milk of all mammals, from which it can be precipitated 

 by addition of acid or of rennet, but not by heat. In the process of gastric diges- 

 tion nuclein is gradually separated from casein. On boiling casein with hydro- 

 chloric acid and stannous chlorid lysatin, C 6 B. 13 N 3 O 2 , results, which yields urea 

 when boiled with baryta-water. 



2. The true nucleins, which consist of albumin plus nucleinic acid. Nucleinic 

 acids are decomposed by hydration into phosphoric acid and xanthin-bases 

 (nuclein-bases) . The latter include xanthin, guanin, adenin, hypoxanthin, cyto- 

 sin. The true nucleins may combine with more albumin and yield nucleo- 

 proteids. A carbohydrate is derived from nucleinic acid, namely pentose. 



The nucleins are insoluble in water or dilute acids, readily soluble in dilute 

 alkalies, with which they unite by reason of their acid character to form neutral 

 combinations. They swell in solution of sodium chlorid, and yield all the color- 

 reactions of albumin. In alkaline solution they are readily decomposed into 

 proteids and nucleinic acids (or phosphoric acid) . The nucleins resist the solvent 

 action of the gastric juice, which is capable of dissolving and digesting only the 

 proteids of the nucleoalbumins and nucleoproteids. Upon the latter property 

 depends the possibility of isolating the nucleins. The nucleinic acids occur also 

 uncombined with albumin in certain cellular structures of the animal kingdom 

 (salmon-spawn). Nuclein-bases have been found free in animal and vegetable 

 tissues. 



The yolk of the egg contains a nuclein-like body containing iron that is 

 utilized in the formation of blood from the yolk (hematogen), and that also 

 aids in hemogenesis on a diet of eggs. From a body, phosphosarcic acid, closely 

 related to the paranculeins, can be prepared a ferruginous body, carniferrin, 

 which contains iron in similar firm combination as in hematogen. 



Nucleohiston, a combination of nuclein and histon, which can be prepared 

 from the erythrocytes of the goose, is readily decomposed into nuclein and histon. 

 The latter prevents coagulation of the blood. 



Nucleoalbumin is prepared by Halliburton in the following manner: Kidneys 

 are rubbed up with powdered sodium chlorid and some water. The expressed 

 extract is poured into distilled water, in which the remains of tissue and 

 the globulins fall to the bottom, while the mucoid nucleoalbumin floats on the 

 surface. This is collected and washed repeatedly with distilled water. 



Injected into the veins nucleoalbumin causes coagulation. According to Pekel- 

 haring, the zymogen of the fibrin-ferment is a nucleoalbumin. Histon, a base 

 consisting of protamin and albumose, is present in the nuclei of the erythrocytes 

 of birds and in leukocytes, thymus, spleen, testicles, in combination with nuclein. 

 It is coagulable by ammonia, not by boiling, and can be extracted by means of 

 dilute acids. Reticulin, the ground-substance of reticular connective tissue, is a 

 related body. It contains phosphorus and sulphur, is indigestible and insoluble, 

 and on heating with alkalies splits off the phosphorus-containing group, and is 

 then soluble with difficulty. With hydrochloric acid it splits off amidovalerianic 

 acid (but no tyrosin). Plastin is similar to nuclein and occurs in the nuclei and 

 in the protoplasm of spermatozoa. It is formed in the process of peptic digestion, 

 and is insoluble in sodium carbonate as well as in hydrochloric acid 4 to 3 of water. 



THE ALBUMINOID BODIES. 



These resemble the true albuminous bodies with reference to their composition 

 and source. They are uncrystallizable ; some of them are free of sulphur; while 

 most cannot be prepared in an ash-free state. Their reactions and decomposi- 

 tion-products resemble those of the albuminous bodies. Some of them yield, in 

 addition to much leucin and tyrosin, also glycin and alanin (amidopropionic acid), 

 although in physiological, chemical and physical respects they exhibit considerable 

 differences from albuminous bodies. They occur in the tissues both as organized 

 constituents as well as in liquid form. Whether they are formed by oxidation 

 from the albuminous bodies or by synthesis is not known. They are in part 

 indigestible, in part digestible, although the products of their digestion can replace 

 the decomposed albumin in the body not at all or but incompletely. They are 



