INTRODUCTORY xiii 
in an ordinary sense has been conclusively proven by various experiments. 
In fact, the majority of venom cytolysins are thermostabile in contradis- 
tinction to the ordinary ferments and are of immense activity, while pepsin 
or trypsin has but little cytolytic property upon the cells freshly taken out 
of a living animal body. Thus, snake venom contains a set of toxic agents 
entirely different from the physiological ferments of other glands. 
Do we, then, have a class of bodies whose mode of action is comparable 
with that of the venom cytotoxins? To this question we answer in the 
affirmative. The presence of cytolytic agents is by no means restricted to 
snake venom, but the phenomena of cytolysis have been constantly observed 
with normal and especially immune serums. The investigations of Landois, 
Buchner, Nuttall, Metchnikoff, Ehrlich, Morgenroth, Bail, Pettersson, Bordet, 
Dungern, Moxter, Schattenfroh, Gruber, Sachs, Landsteiner, Flexner, 
Noguchi, and others are sufficient to prove the wide occurrence of normal 
and immune cytolysins in the blood serum. 
Through the classic works of Bordet, Erhlich, and Morgenroth the mechan- 
ism of cytolysis occasioned by normal or immune serums has been shown to 
be due to two constituents, which must cooperate to produce this effect. 
Serum cytolysins are specific, and the specificity has been shown to be caused 
by one of the constituents concerned in cytolysis and is capable of being 
increased through artificial immunization. This is Ehrlich’s amboceptor 
and Bordet’s substance sensibilisatrice. The second constituent taking part 
in cytolysis is increased with difficulty by the immunization and is present 
in all normal as well as immune serums. This is Ehrlich’s complement and 
Bordet’s alexine. Its function is to inflict injury upon the cells already 
treated with the specific ambocepter or substance sensibilisatrice. 
What, then, is the relation between the mechanism of serum cytolysis and 
that of venom cytolysis? Many differences have been noted to exist in these 
two sets of cytolysis. 
Flexner and Noguchi first demonstrated that venom cytolysis bears a 
general resemblance to serum cytolysis, as the mechanism of solution of cells 
is of a dual or complex nature, though this apparent parallelism has later been 
found to be only partial. 
In venom cytolysis the complementary substances are sometimes inherent 
to the cell itself, thus setting forth examples never met in the case of serum 
cytolysis. The amboceptor or substance sensibilisatrice of snake venom is 
much more thermostabile than that of serum, and many amboceptors in venom 
retain their activity even after brief boiling. 
While a finer analysis of serum cytolysis has become a matter of extreme 
difficulty and has added little to that which was brought out by the investiga- 
tions of Ehrlich and Bordet several years ago, the nature of venom cytolysis 
has been much more profitably studied in recent years. It may be con- 
sidered safe to say that our knowledge concerning the venom cytolysis has 
broken through the boundary of pure biological-physiological domain and is 
now wandering in the biochemical realm. This advance has been the fruit 
