PHYSIOLOGY: BENEDICT AND MURSCHHAUSER 
597 
the mean, as the red coiTLponent of the double is the stronger of the two. 
In other words a nebular line of sHghtly greater wave-length than 4649. 2 A 
would meet the requirements. There is actually such a line at 4649.5A. 
Both this and the one at 4267A probably exist as bright bands in the 
spectra of the Wolf-Rayet stars. ^ 
The following is a summary of the wave-length comparisons which 
have been made: 
Star. 
Nebula Nitrogen Carbon 
4097.6 4097.5 
4267.28=1= 4267.30 
4649.5 4649.2 + 
In considering the significance of these comparisons it should be borne 
in mind that the observations of the nebulae were made with a single 
prism spectrograph and that the lines are faint and difficult to measure. 
I think, however, that the evidence renders probable the presence in 
the nebulae of carbon and nitrogen, and fortifies the assumption of a 
close relationship between the nebulae and the early type stars. 
There are other possible points of correspondence between nebular 
and stellar spectra which will be referred to in a more complete presen- 
tation of the subject. 
^Pub. Ast. Obs. Univ. Mich., 1, 120 (1915). 
2 London, Proc. R. Soc, A, 82, 534 (1909). 
3 Ibid. 
* A paper is just at hand by Mr. T. R. Merton, entitled: On a spectrum associated with 
carbon, in relation to the Wolf-Rayet stars, Lond., Proc. R. Soc.f A, 91, 498 (1915). In 
this the author makes the suggestion that the two Wolf-Rayet bands in question, with others, 
are due to carbon. 
ENERGY TRANSFORMATIONS DURING HORIZONTAL 
WALKING 
By Francis G. Benedict and Hans Murschhauser 
NUTRITION LABORATORY, CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, November 2, 1915 
No form of muscular exercise enters so universally into the lives of 
all individuals as does horizontal walking, but most of the earlier re- 
searches on the energy transformations consider walking on a hori- 
zontal plane as incidental to or as a base-Une for the work of ascent, 
particularly in connection with mountain cHmbing. From the funda- 
mental contributions of Zuntz and Durig and their associates, it has 
been concluded that for an individual walking on a horizontal plane 
the energy required to move one kilogram, either of body-weight or of 
