Pituitary Extract. 



125 



is positive. The line may be visible to the unaided eye in un- 

 treated bones. The results of the examination of the gross 

 specimen should be confirmed by study of celloidin or frozen 

 sections from the other half of the bone or other bones. Control 

 rats and rats which fail to give the test do not show the line of 

 calcification. The new line of calcification may extend completely 

 across the bone or may be incomplete or fragmentary, according 

 to the extent of the deposition of the lime salts induced by the 

 substance which is under examination. Since complete starvation 

 also causes the typical linear deposit of lime salts to appear in the 

 cartilage of rachitic animals, the food intake of both test and 

 control rats must be carefully watched during the course of the 

 experiment. Control and test animals must be kept under iden- 

 tical conditions. 



This method is applicable to the study of the calcium deposit- 

 ing-power of any chemical substance or physical force. 



61 (1808) 



The effects of pituitary extract on the body temperature of animals 

 rendered poikilothermous by destruction of the optic 

 thalamus. 



By FRED T. ROGERS. 



[From the Department of Physiology, Baylor Medical College, 



Dallas, Texas.] 



In earlier work the writer has shown that destruction of the 

 cerebral hemispheres and the optic thalamus of birds reduces the 

 animal permanently to a poikilothermous condition. In birds 

 this is not an operation that leads to immediate death for they 

 may be kept alive for one to three months by keeping them con- 

 stantly at an atmospheric temperature of 30 0 to 35 0 C. The 

 routine procedure was to remove the cerebral hemispheres in toto 

 by the scalpel and then destroy the optic thalamus with an 

 electro-cautery. 



It has been pointed out elsewhere that to produce the poi- 

 kilothermous condition there must be extensive destruction of 

 the thalamus and that localized injuries did not appreciably change 



