1162 
The same applies to the immune sera against the cells of various 
organs °). [ 
As far as the globulins of milk are concerned it may be accepted 
as highly probable and experience goes to prove, that they behave 
quite similarly to the serum-globulin, and the same may be said 
for all proteins which have a very similar chemical composition as 
the serum-proteins as regards the kind and quantity of the amino- 
acids which build up their molecule. 
But when one considers proteins such as haemoglobin which in 
their chemical struetures i.e. in their construction out of amino-acids 
differ widely from the proteins of the serum, a note-worthy problem 
presents itself. 
If these bebave in regard to the species specificity similarly to the 
serum protein, two possibilities present themselves: either the 
species-structure in such proteins and in serum proteins is realised 
in wholly different and independent wavs, or else there is a relation 
in this way that among the different proteins of a species one 
corresponding smaller ov larger group (or several groups) of the 
molecule is the bearer of the species-specificity. 
In the latter case the problem would arise of demonstrating this 
species-specific nucleus. In the other and perhaps less probable case 
there would be a similarity of chemical structure of two homologous 
proteins in related animal-species, but no chemical similarity would 
be found between the different proteins of the same species. From 
this it appears indicated to investigate the different proteins as to 
their species-specificity and I have, therefore, undertaken the investi- 
gation of the precipitins against haemoglobin. This substance is 
well suited for the examination of the question raised because the 
composition of its protein constituent i.e. of globin varies widely 
from that of serum globulins and serum albumins. 
LeBLANC*®), Ipk*) and Demees®) were the first to report on the 
formation of precipitins against haemoglobin. THOMSEN °) investigated 
the question of species-specificity and came to the conclusion that 
anaphylaxis against erythrocytes is to a certain extent species-specific. 
The greater number of his experiments, as also the researches of 
1) SaLus. Bioch. Zeitschr. 60. 1. 1914. 
2) La Cellule 18. 337. (1901). 
Bee » 20. 263. (1902). 
| » 84, 423. (1907). 
5) Zeitschr. f. Immunitatsf. 3. 539. (1909). Cf. WeicHarpt. Zeitschr. f. Immunitatsf. 
14. 609. (1912). On the specificity of haemoglobin crystals. cf. ReicHert a. BROWN, 
Carnegie Institution Publication Washington 1909. 
