THE PR TEWS OF MILK. 1 3 9 
clot with rennet at all; when it does so, the clot is a iiocculent 
precipitate, which frequently redissolves rapidly in excess of gastric 
juice. According to Szontagh, 3 human caseinogen yields no pseudo-nuclein 
on gastric digestion; this was confirmed by WroblewsM, 2 who found 
also that human caseinogen has the following percentage composition — 
C, 52-24; H, 7 31 ; N, 14-9; P, 0-68; S, 1117; 0, 23-66. This, it will 
be seen, is different from the composition of the caseinogen of cows' milk. 
Human caseinogen contains phosphorus, but not in the form of pseudo- 
nuclein, as in cows' milk. 
Wroblewski finds that human milk contains small quantities of lact-albumin, 
and of another proteid very rich in sulphur (4 '7 per cent.) and poor in carbon 
(45-01 percent.). Lehmann and Henipel 3 find that the caseinogen of cows' 
milk contains 7*2 per cent, of ash; this consists of CaO, 49"5; MgO, 2 - 4; 
P.,0 5 , 47 -0; and S0 o 1'06 per cent. The elementary composition of the 
proteid is given as C/50-86 ; H, 6-72 ; N, 14-63 ; P, 0-81 j S, 0'72 j ash, 6-47 
per cent. The caseinogen of woman's milk contains more sulphur, P09, and 
less ash, 3'2 per cent. Some of the differences between the two caseinogens 
are doubtless dependent on the amount and nature of the ash with which they 
are associated. 
The occurrence of nucleon (phospho-carnic acid) in milk has already been 
mentioned on p. 104. Siegfried 4 states that the nucleon accounts for 41 -5 per 
cent, of the phosphorus in human milk, but for only 6 per cent, of that in 
cows' milk. Practically all the phosphorus in human milk is in organic com- 
bination (nucleon and caseinogen). 
Zact-albumin. — After the precipitation of caseinogen and lacto- 
globulin by half-saturation with ammonium sulphate, lact-albumium re- 
mains in solution. It can be incompletely precipitated from this solution 
by saturation with sodium sulphate. It is completely precipitated with 
the other proteids when milk is saturated with ammonium sulphate. It 
coagulates between 70° and 80° C. ; in cows' milk at 77° G. It is not 
separable, like serum albumin and egg albumin, into several proteids by 
fractional heat coagulation. It, moreover, is coagulated by heat very 
slowly ; the solution must be kept some hours at 77° C, before it is 
completely precipitated. Its specific rotatory power 5 a B = -36°, i.e. less 
than that of serum albumin ; it has the following percentage composi- 
tion : C, 52-19; H, 7-18; N, 15-77; S, P73; O, 2313. The high 
percentage of sulphur is another distinction between it and serum 
albumin. 
Ladoglobulin. — A trace of globulin is obtained from cows' milk by 
saturating it with magnesium sulphate, after the removal of the 
caseinogen by saturation with sodium chloride (Sebelien). Its 
characters are like those of serum globulin. The amount of globulin in 
colostrum is considerable, but in fully-formed milk it is present in so small 
an amount that for a long time I was unable to confirm Sebelien's state- 
ment. Hewlett, 6 however, who worked with me, confirmed its presence. 
1 Ungar. Arch. f. Med., Wiesbaden, Bd. i. S. 192; Jaltrcsb. ii. d. Fortschr. d. Thier- 
Chem., Wiesbaden, Bd. xxii. S. 168. 
2 Inaug. Diss., Bern, 1894. See also Moraczewski, Ztschr. f. physiol. CJiem., Strassburg, 
1894, Bd. xx. S. 28. 
3 Arch.f. d. ges. Physiol., Bonn, Bd. lvi. S. 558. 
4 Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxii. S. 575. 
5 Sebelien, Jahrcsb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xv. S. 184. 
6 Jonrn. Physiol., Cambridge and London, 1892, vol. xiii. p. 798. See also Arthus, Arch. 
de physiol. norm, etpath., Paris, 1893, p. 673. 
