54 THE ALBUMINS. 



pentoses, it was termed paranuclein (Kossel) or pseudonuclein 

 (Hammarsten). At present there is a tendency to separate the 

 nucleo-albumins from the nucleoproteids, as further investigation 

 has shown that barring the presence of phosphorus there is very 

 little similarity between the two. It has been ascertained, more- 

 over, that they probably do not enter into the construction of 

 the nucleins ; and as they resemble the globulins in many re- 

 spects, Cohnheim has suggested that the term nucleo-albumins be 

 abandoned and replaced by phosphoglobulins. They are nevertheless 

 related to the nucleoproteids, as there are conditions (as in the de- 

 veloping organism) under which the body unquestionably constructs 

 its true nucleoproteids from this source. For this reason and the 

 phosphorus content I have given the group an independent position 

 intermediate between the native albumins and the proteids. 



The group comprises some of the most important food-stuffs, such 

 as casein, the vitellin of egg-yolk, certain nucleo-albumins of cell- 

 protoplasm, the phytoglobulins or phytovitellins of the leguminous 

 plants, the ichthulin of fish eggs, etc. Some of these can be ob- 

 tained in crystalline form. All of them probably contain iron. Ele- 

 mentary analysis of some of the bodies has given the following 

 results : 



Casein (Hammarsten) . C=52.90 H=7.05 N=15.65 8=0.758 P=0.847 



Vitellin (birds' eggs). . 0=42.11 H=6.08 N=14.73 S=0.55 P=5.19 Fe=0.39 



(Bunge's hsematogen) 



Ichthulin (fish eggs) . . 0=53.52 H=7.71 N=15.64 8=0.41 P=0.43 Fe=0.1 



Cellular albumin . . . C=52.37 H=6.81 N=17.23 8=1.06 P=0.42 



(snail liver) 



Phytovitellin(Paranuts) . C=52.43 H=7.12 N=18.1 8=0.55 P 



Legumin (peas) .... C=51.74 H=6.90 N=18.0 8=0.42 P- 



The ichthulin and the helicoproteid which Hammarsten discov- 

 ered in the albuminous gland of a snail (Helix pomatia) were 

 formerly placed in a separate category, the so-called phosphogluco- 

 proteids, as they contain a large amount of reducing substance in 

 their molecule ; they are both, no doubt, true nucleo T albumins. 



The nucleo-albumins have markedly acid properties and are almost 

 insoluble in water. They form salts with the alkalies and ammo- 

 nia, and these are readily soluble ; on treating such solutions with 

 acids the free nucleo-albumins are again precipitated. The solu- 

 tions of the salts are not coagulated by heat, but with some this can 

 be effected when the reaction is very faintly acid, so faintly that acid 

 precipitation does not occur as yet. They are precipitated from 

 their solutions by salting, and more readily so even than the globu- 

 lins. 



On peptic digestion pseudonuclein is thrown down at a certain 

 phase of the process ; this contains more phosphorus than the 

 mother-substance. Apparently it contains a paranucleinic acid 

 radicle. Levene has isolated a substance belonging to this order 

 from birds' eggs (his avivitellinic acid), and there is evidence to show 



