E. B. BLACK AND J. M. STENGLE 
453 
rocytes which were J negative but which had 
serologically detectable J substance in the 
serum. Thus three phenotypes were identified in 
the J system: J<=« with J substance present on 
red cells and in the serum ; J« with J substance 
in the serum but not detectable on the red cells 
by the usual typing procedures ; and with no 
detectable J substance. 
Although J substance is present in the sera of 
both and J<^^ individuals, its concentration 
(measured in units of J where one unit is equal 
to the reciprocal of the highest dilution of 
strongly reactive J reagent giving 50% or 
greater hemolysis within 4 hours^^) is usually 
much higher in the serum of J" cattle than in 
the serum of cattle. The Initial hypothesis 
suggested that the higher serum concentration 
was necessary for J substance to appear on the 
erythrocytes. 2^ However, exceptions to this 
were noted. Of the 194 animals typed by Stone, 
et al., (Figure 5) 70 were of the class P. Of the 
P individuals only 4 had serum J levels greater 
than 16 units. Of 124 J<^« cattle 102 liad serum 
J levels above 16 units, 15 had serum J levels of 
exactly 16 units, and 7 had serum J levels of 
less than 16 units. If 16 units of serum J sub- 
stance represented a threshold above which 
erythrocytes tended to adsorb J substance and 
below which they tended not to adsorb J sub- 
stance, then in this study the 4 individuals 
RELATIONSHIP BETWEEN UNITS OF J SUBSTANCE IN THE SERUM AND 
ON THE CELLS OF 194 DIFFERENT CATTLE BLOODS 
>256 
256 
32 
16 
<2 
1 
1 
2 
1 
2 
14 
6 
2 
1 
3 
7 
26 
8 
8 
1 
1 
3 
2 
4 
4 
5 
3 
1 
1 
2 
1 
2 
1 
1 
1 
2 
1 
1 
1 
3 
1 
19 
13 
9 
17 
8 
3 
1 
0 <2 2 4 8 16 32 64 128 256 >256 
UNITS OF J SUBSTANCE IN THE SEBUM 
Figure 5. — Relationship between units of J substance 
in the serum and on the cells of 194 different cattle 
bloods'^ 
100- 
90- 
SO- 
TO- 
60- 
% 60- 
40- 
30- 
20- 
10- 
m 
I I Cattle. 
UNITS OF SERUMJ 
I Strong J^='"Cattle. 
i Weak J" Cattle 
Figure 6. — Relationship of serum and cellular J of 
966 J" and J" cattle over one month of age"' 
with serum J greater than 16 units and the 7 
J" individuals with serum J less than 16 units 
represented exceptions to the rule. In larger 
samples of cattle, 2% showed J" red cells in the 
presence of greater than "threshold" concentra- 
tion of serum J and about 4% showed J"^ red 
cells in the presence of a below "threshold" con- 
centration of serum J. Thus it appeared that 
other factors in addition to the serum J concen- 
tration might be operative in determining 
whether or not the red cells acquired J sub- 
stance. 
Further investigations by PateP®'^^ con- 
firmed the assumption that serum concentration 
of J substance is one factor, but not the only 
factor, playing a role in the acquisition of J sub- 
stance by cattle red cells. The relationship be- 
tween the concentrations of serum and erythro- 
cytic J substance was analyzed in 966 cattle 
(Figure 6). The J'^^ phenotype was divided into 
strong J<=^ (greater than 30 units of cellular J 
substance) and weak J^^ (less than 30 units of 
cellular J). The distributions of strong 1"=% 
weak J'^^ and were analyzed as a function of 
J concentration in the serum. Again there was 
evidence that there is a direct relationship be- 
tween serum J concentration and the adsorption 
of J substance to the erythrocytes. In Patel's 
data a threshold range of about 25-34 units of 
serum J substance existed above which 86% of 
the cattle had red cells which had acquired 
enough J substance to be J positive by routine 
tests and below which 86% were J negative by 
