INTRODUCTION. 3 



that the granules consist of a proteid rather than a lipoid material, although a 

 mixture of both may be present. 



After addition of slightly hypertonic salt solution, a relatively stable sus- 

 pension of granules (with some admixture of nuclei) can be obtained, and 

 through centrifugation it will perhaps be possible to separate the granules and 

 the liquid part of the venom. A comparison of the toxicity of these two con- 

 stituents of the venom could thus be made and direct proof obtained of the 

 significance of the granules in the production or fixation of the venom. 



There exists much difference of ojiinion in regard to the real function of the 

 poison gland. Does it merely take up from the blood the poisonous material 

 produced by other cells, or does it actually manufacture the venom from non- 

 poisonous substances supplied through blood or lymph? Calmette and Faust 

 accepted the first view. In snakes the blood and, as Flexner and Noguchi 

 found, even the ova contain a venom very similar to that secreted by the poison 

 gland. Calmette and Faust believe, therefore, tliat the cells of the poison 

 gland have a selective affinity for the venom circulating in the blood. Inas- 

 much as Calmette noticed that the heat resistance of the poisonous substance 

 present in the blood differs somewhat from that of the venom secreted by the 

 poison gland, he assumes that a precursor which is poisonous and has been 

 produced by other cells is slightly modified in the poison gland and then 

 secreted. This difference in the heat resistance of the two poisons he regards 

 as a reason sufficient to exclude the view of Phisalix and Bertrand, who regard 

 the venom circulating in the blood as being manufactured in the venom gland 

 and eliminated in the blood through a mechanism related to internal secretion. 

 They found, accordingly, that after extirpation of the venom gland of snakes 

 the blood lost its toxic properties. 



In Heloderma conditions are less complicated. Here the venom can not 

 be found anywhere in the body except in the poison gland. Neither does the 

 blood become poisonous after extirpation of the poison glands, as should be 

 expected if the poison glands served merely as a place of elimination for the 

 venom prepared elsewhere. We can therefore be certain that in the case of 

 Heloderma the poison gland is the place where the venom is produced out of 

 non-poisonous material carried to the gland. Such a conclusion is also in 

 accordance with the view that the granules of the gland are the carriers of the 

 venom. 



In its action on animals the venom of Heloderma bears a close resemblance 

 to the A'enoms of some snakes, especially the Colubridse. It affect s mainly the 

 central nervous system. The marked local, especially the hemorrhagic, effects 

 that characterize the venom of some vipers are absent. It affects very early 

 the respiratory center and, as in the case of cobra venom, death is mainly due 

 to a failure in tlie action of this center. Accordingly, we may find, even 

 within the first Four'after injection of the venom, microscopic changes in the 

 ganglia-cells. The changes here are therefore noticeable at least as early as in 

 the case of snake venoms that have been investigated from this point of view; 

 but the changes do not go so far as after injection of the venom of some Colu- 



