Papers ON PHYSICS: 
Visible Color Effects in a Positive Ray Tube Containing Helium 
(Abstract), Chas. T. Knipp, University of Illinois ......00000..... 283 
A Simple Demonstration Tube for Exhibiting the Mercury Ham- 
mer, Glow by Mercury Friction, and the Vaporization of Mer- 
cury at Reduced Pressures (Abstract), Chas. T. Knipp, Uni- 
ISSTEMS CE TAPPING) yes coet eka dns auv en sh bocce aeeeleg eee ce ect ar as oe ates As 284 
An Improved Form of High Vacuum High Speed Mercury Vapor 
Air Pump (Abstract), Chas. T. Knipp, University of IIlli- 
The Rate of Combustion of Some Illinois Coals, Fred D. Barber, 
iiknots: State Normal University... -osbese gece ete 287 
Indoor Humidity, Fred D. Barber, Illinois State Normal University 294 
Papers oN ZOOLOGY AND PHYSIOLOGY: 
Selection, Regression, and Parent-Progeny Correlation in Aphis 
Avenae Fab., H. E. Ewing, Iowa State College ...................-......-- 303 
Amphibians and Reptiles of the Charleston Region, T. L. Hankin- 
son, state Normal School; (Charleston: ...2- 2-2-2222 soe ee 322 
Crane Town Destroyed, W. S. Strode, Lewiston ...............2:.sseceeceeeee 330 
The Effect of Starvation on the Catalase Content of Tissues, 
Alma}. Nell: University, of IWhinois 2.02.2 332 
SONSTEDU TION: AND (BS YeRAWSi ott ceesere tc lacceate ccsee veces cucu le 2s, Seen eepenE ag 337 
IPPC COE IWS ARIS sae ee I ed SC 339 
