290 The American Naturalist. [March , 
PHYSIOLOGY. 
Vasomotor Nerves of the Portal Vein.—Mall' makes an 
important advance by finding experimental evidence of the existence 
of vasomotor nerves in the portal vein. This strengthens the idea 
that this vein and its branches play the rôle of arteries with reference 
to the capillaries of the liver. If the flow of blood from the aorta to the 
alimentary canal be stopped, and the splanchnic nerve be stimulated, a 
narrowing of the portal vein may be detected. If the stimulation be 
continued, the lumen entirely disappears ; at the same time there is an 
increase in arterial pressure. The subject is to be investigated more fully. 
Relation between Molecular Weight, Molecular Struc- 
ture, and Physiological Action.—Recent work of Giirber? on 
the physiological action of lupetidine and related substances has led 
Gaule? to the conclusion that it is not the weight or size of the mole- 
cule that determines the physiological action, but the latter is the 
product of the effects of the different components of the molecule. 
If, then, a gradual increase in molecular weight be brought about by 
the continued addition of a CH, group, for example, similarly placed 
in the molecule, the physiological effects of the compounds so pro- 
duced will be similar, varying only in degree; but if an NH, group 
be added instead of a CH, group, the increase in molecular weight 
will be essentially the same, but the physiological effects will be dif- 
ferent. Thus the physiological effects of drugs will vary with the 
molecular weight, only when the variation in the latter results from an 
increase or decrease in the number of identical atomic groups. A 
second point established by Giirber’s work is that different groups 
of atoms act differently, and that these different groups act On 
different sets of organs. This would suggest the idea that the 
living substance in each system of organs represents a peculiar chemical’ - 
proportion ; certain groups of atoms in the body immediately entering 
into combination with certain groups of atoms in the molecules of 
substances taken in.—L. G. 
Life-History of Blood Corpuscles.—A valuable addition to 
the literature of the blood corpuscles has appeared recently in the 
1 Archiv fiir Anatomie und Physiologie. Phys. Abth., Suppl. Bd., 1890. 
? Archiv f. Anat, u. Phys, Physiol Abthlg., 1890, p. 401. 
3 Ibid., p. 478. 
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