9 8 



Scientific Proceedings (65). 



temp. 104. 2 0 F., marked tonic and clonic muscular contractions. 



Experiment II. Dog 9. Weight 15.9 Kilos. Age 12 Months. 



1st set of obs. (average of 10 readings) Coag. time z l A min., normal. 



2d " " " " " " " " " 4 " " 



3d " " " " " 8 " " " 3 " during slight tetany. 



No symptoms appeared until nine days after operation and 

 then only slight muscular tremors were observed with no rise of 

 temperature (100. 6° F.). 



Experiment III. Dog 9. Weight 14.0 Kilos. Age 12 Months. 



1st set of obs. (average of 10 readings) Coag. time 5 min., normal. 



2d " "5 



3d " " " " " " 4^2 " after operation. 



This dog showed slight symptoms three days after operation. 

 These passed off and did not return and fifteen days later the 

 third set of observations was made after which the animal was 

 killed. 



60 (992) 



The relative efficiency of the biological action of the Roentgen rays 

 emitted by the Coolidge and the old type tubes. 



By Isaac Levin. 



[From the Department of Cancer Research of the Montefiore Home.] 



In accordance with the modern conception in physics the 

 Roentgen rays present pulsations in the ether analogous to the rays 

 of light. The waves of ether forming the Roentgen rays are con- 

 siderably shorter than the shortest ultra-violet waves of light. 

 The waves of the so-called soft Roentgen rays are about 1,000 

 times shorter than those of ultra-violet light, and the waves of the 

 hard Roentgen rays are still shorter. 



Any substance, solid, liquid, or gaseous, absorbs a part of the 

 Roentgen rays which pass through it. The fraction of the rays 

 thus absorbed depends upon the density and thickness of the 

 substance. The remaining rays penetrate beyond the interposed 

 substance. The relation between the quantity absorbed by the 

 substance and that penetrating beyond it is of fundamental im- 



