44 THE ALBUMINS. 



characterizes one of the three large molecular complexes which to- 

 gether form the albuminous molecule, viz., the gluco-complex. As 

 has been seen, this can be obtained as a primary product of proteo- 

 lysis in the form of a gluco-albumose, which contains the entire 

 carbohydrate group of the original molecule. Notably in the mucins 

 and mucoids, but also in some of the native albumins in the 

 narrower sense of the term, such as ovalbumin, serum-albumin, and 

 the mixed globulins of the blood-serum, this complex is obtained on 

 hydrolysis as an ammo-sugar, and usually as glucosamin ; less 

 commonly, as in the case of the mucin derived from the frog's so- 

 called albuminous gland, as a galactosamin. These bodies, however, 

 probably do not occur preformed in the albuminous molecule, but 

 as higher carbohydrates, viz., as disaccharides or polysaccharides. 

 According to Miiller, the mother-substance of glucosamin is a poly- 

 meric acetylated glucosamin (FriinkePs albamin). 



Whether or not the glucosamin complex is found in all albumins 

 in which a carbohydrate radicle can be demonstrated, is not known. 

 In any event it is not the only carbohydrate group that may occur. 

 This is notably the case with the nucleoproteids, all of which appar- 

 ently contain a pentose group. This group is a part of the 

 nucleinic acid radicle of the nucleoproteids, and it is possible that 

 an additional carbohydrate group (perhaps glucosamin) may be con- 

 tained in the albuminous radicle which is in combination with the 

 nucleinic acid complex. Kossel could demonstrate the presence of 

 a hexose also in the nucleoproteid of the thymus, of yeast, and in 

 the nucleinic acid of the sturgeon's testicles, by isolating laevulinic 

 acid from the products of decomposition. The pentose obtained 

 from the nucleoproteid of the pancreas was /-xylose. 



The amount of reducing substance (glucosamin) which can be 

 obtained from the different albuinins differs considerably. The 

 largest quantities have been obtained from mucins and mucoids 

 (30-40-f per cent.). This fact has led to the establishment of a 

 separate group of albumins, the gluco-albumins (glucoproteids), 

 which is distinguished in this manner from the common albumins. 

 This division is quite arbitrary, as the latter also contain a carbo- 

 hydrate group, though it is present in most of them in much 

 smaller amount (serum-albumin 0.5 per cent.). Crystallized ovalbu- 

 min with 15 per cent, occupies an intermediate position, inclining 

 toward the mucoids. Casein is apparently the only animal albumin 

 which is without a carbohydrate group, while among vegetable albu- 

 mins, according to Osborne, this is more frequently the case. 



Regarding the quantitative distribution of the primary radicles in 

 the different albumins our knowledge is still quite defective, but 

 with better methods is rapidly becoming extended. The more 

 important data have been embodied in the accompanying table. 

 From this it will be seen that barring the protamins all albumins 

 have essentially the same component radicles, but that the individual 



