ENDOCRINE SYSTEM 



161 



vations on the effects of thyroparathyroidectomy and of para- 

 thyroidectomy. A condensed summary of the more important 

 results is here presented. The groups from which the entire 

 thyroid apparatus had been removed are briefly designated as 

 "Thypars" and those from which the parathyroids alone had 

 been removed as "Parathys." 



50 100 150 



200 250 JOO 350 



450 



500 520 



Chart 19 Showing the changes in the intestine-contracting power of equiv- 

 alent amounts of thyroid extracts from male and female albino rats according to 

 age. 



In the series of studies now complete, the operation was made 

 at 100 days of age and the animals were killed at 150 days. Iq 

 a less complete series, still in progress, the operation was made 

 at 75 days and the killing as before, at 150 days. Unless other- 

 wise stated, the conclusions are based on rats operated at 100 

 days of age. Condensed data table 117. 



As previously noted (p. 134) these operations, both of which 

 involve removal of the parathyroids, were accompanied by the 



