480 
Journal of Agricultural Research 
Vol. XXIX, No. io» 
experiments there was, with one excep¬ 
tion, a greater amount of formalde¬ 
hyde combined when a greater amount 
was added. 
That the presence of salts is neces¬ 
sary for the formation of gels has been 
shown in the preceding paper. While 
the part played by salts has not been 
investigated, it has been noted that a 
greater part of the noneuglobulin pro¬ 
teins of the serum may be converted 
into euglobulins within a few hours 
and the serum yet fail to gel within 
many days. If salt is added to such 
formolized serums, they gel within a 
short time. This would suggest that 
the presence of salt, although necessary 
for gelatification, is not necessary for 
the transformation of the more soluble 
proteins into euglobulins. 
DISCUSSION 
It has been shown by Moll (8), 
Banzhaf (I), and others that an expo¬ 
sure of serum to a temperature of 50° 
to 60° C. for more or less prolonged 
intervals results in the transformation 
of albumins into pseudoglobulins and 
the latter into euglobulins. If the 
temperature to which the serum is 
exposed is sufficiently high, coagula¬ 
tion, of course, results. On the addi¬ 
tion of formaldehyde to serum a simi¬ 
lar transformation of the proteins 
occurs. If the concentration of the 
formaldehyde, other factors not pre¬ 
venting, is sufficiently high, gelatifi¬ 
cation results. 
According to Chick and Martin (3), 
the reaction involved in the ; heat 
coagulation of protein increases in 
velocity with increase of temperature 
and they give 8 as the temperature 
coefficient of the heat coagulation of 
hemoglobin. The experiments report¬ 
ed in this paper indicate that the trans¬ 
formation by formaldehyde of the more 
soluble serum proteins into euglobulins 
increases in velocity with increase of 
temperature. The temperature coeffi¬ 
cient is 3. 
Mann ( 6 , p. 318) states, and S0rensen 
and Jurgensen (16) confirm him, that 
any protein solution containing salts, 
acids, or bases becomes more alkaline 
on being coagulated. Although the ad¬ 
dition of formaldehyde to serum results 
in a primary increase in acidity, this is, 
as has been shown herein, always fol¬ 
lowed by a decline in titrable acidity, 
and this decline may continue until the 
serum is more alkaline than it was in 
the beginning. 
It is well known that native serums 
diluted with five or more parts of water 
do not coagulate on being heated, but if 
salt is added to such diluted and heated 
serums a coagulum is produced. This 
can be explained by the fact that heat 
coagulation of proteins consists, as 
shown by Chick and Martin and quoted 
by Robertson (12, p. 307) of two pro¬ 
cesses, (a) denaturation and (b) agglu¬ 
tination, and this occurs only in pres¬ 
ence of salt. It has been shown in this 
study that the addition of formaldehyde 
to serum causes (a) denaturation, i. e., 
the conversion of the more soluble pro¬ 
teins into less soluble forms, and (b) 
gelatification, which latter condition, so 
far as the writer’s observations go, oc¬ 
curs only in the presence of salts. 
Chick and Martin (3) have shown 
that heat coagulation of proteins is not 
an instantaneous process, but that it 
proceeds with a definite velocity. In 
the work reported herein, it has been 
shown that the transformation by for¬ 
maldehyde of the more soluble serum 
proteins into euglobulins, the end result 
of which is gelatification, is not an in¬ 
stantaneous process but that it also 
proceeds with a definite velocity. 
From the foregoing it seems apparent 
that an analogy exists between the 
mechanism of heat coagulation on the 
one hand and of formal-gelatification 
on the other. However, at a certain 
point the analogy ceases, for while the 
reaction concerned in the heat coagula¬ 
tion of serum belongs to the first order, 
the reactions concerned in formol-gelar 
tificatjon seem to belong to the second 
order. 
Robertson (12, p. 309) states that 
heat coagulation ‘ ‘is essentially a 
phenomenon of dehydration of which 
the first stage, that of internal neutral¬ 
ization through the loss of the elements 
of water from the end —NH 2 and 
COOH groups, probably corresponds to 
the phenomenon of denaturation while 
the subsequent or simultaneous polym¬ 
erization of these anhydrides leads to 
the formation of particles so large as 
to assume the properties of matter in 
mass, i. e., flocculi.” He states that 
Mann, Sutherland, Hofmeister, and 
Pauli have expressed similar views. 
The points of similarity and con¬ 
trast between the mechanism of the re¬ 
actions which occur during heat coagu¬ 
lation and formol-gelatification have 
suggested a possible explanation of the 
latter phenomenon. It will be recalled 
that an immediate increase in titrable 
-acidity followed the addition of for¬ 
maldehyde to serum. This may be 
considered as the first stage in the re¬ 
action and may be explained, perhaps, 
by the occurrence of reactions resem¬ 
bling the reaction which takes place 
between amino acids and formalde- 
