PHYSIOLOGY: A. G. MAYER 
37 
fore be stated that, notwithstanding the many difficulties in the way of 
such studies among primitive peoples, there have been made some 
serious beginnings in this very important line of anthropological inves- 
tigation. As to detailed results, nothing can be said until a careful 
and necessarily tedious elaboration of the data is completed. 
The third main object of anthropological field work under the auspices 
of the Smithsonian Institution during the last three years was the search 
in Asia for probable traces of the ancient stock or stocks of mankind, 
from which the American Indians were derived. On this subject a num- 
ber of preliminary reports have already been published"* and it is unnec- 
essary to do more in this place than to state that such traces undoubt- 
edly exist in Asia to this day, that they extend over a very large 
territory, and that they are soon to receive further attention by the 
Smithsonian Institution. 
* See bibliography in A. A, Ivanovskiji, Ob Antropologiceskom Sostave Naselenii Rossii, 
Moskva, 1904. 
2 See HrdliJka's The Painting of Human Bones, etc. Smithsonian Inst. Rep. for 1904. 
3 Published in Smithsonian Inst., Bull. Bur. Amer. Eth., No. 34. 
* Symposium on The Problems of the Unity or Plurality and the Probable Place of Ori- 
gin of the American Aborigines, Amer. Anthrop., 14, No. 1, Jan.-March, 1912; Restes, 
dans I'Asie orientale, de la race qui a peupl6 rAm6rique, Congres International d' Anthro- 
pologic et d'ArchSologie prihistoriques, Compte Rendu de la XIV Session, Geneve, 1912; Re- 
mains in Eastern Asia of the Race that Peopled America, Smithsonian Inst., Misc. Coll., 
60, No. 16; The Derivation and Probable Place of Origin of the North American Indian, 
Proc. XVIII International Congress of Americanists, and the Genesis of the American 
Aborigines, Proc. II Pan-American Sci. Congress, Washington, 1916. 
A THEORY OF NERVE-CONDUCTION 
By Alfred Goldsborough Mayer 
DEPARTMENT OF MARINE BIOLOGY, CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, November 16, 1915 
This research is a continuation of the studies reported in these Pro- 
ceedings, 1, 270, May 1915, and it will therefore be unnecessary to 
redescribe methods of experimentation. These later experiments were 
made at the Marine Laboratory of the Carnegie Institution of Washing- 
ton at Tortugas, Florida, in July, 1915, and the kymograph records were 
studied in detail in a room which the writer was privileged to occupy in 
Guyot Hall, Princeton University. 
In the experiments of 1914 the distilled water contained between 10"^ 
and 10~^ H ion concentration due to carbon dioxide, thus giving an ex- 
cess of free H ion. The endeavor was therefore made in July, 1915, to 
obtain neutral distilled water in which both the H and the OH ion con- 
centration approached 10-"^. Accordingly, following the suggestion of 
