Effect of Thyroid-feeding and of Thyro-parathyroidectomy. 103 



No appreciable difference is obtained between the action of the material 

 from the three groups of animals. Immersion of the uterus in each solution 

 was limited to lift'een seconds, and both height and duration of contraction 

 are the same in the normal, thyroid-fed, and parathyroidectomised material. 



^- Z Tf. T. 



Fig. 1. — Effect upon the isolated uterus of the virgin rat of immersion in O'OOl per cent. 



extracts of dried pars nervosa of the pituitary body. 

 N., extract derived from normal cats ; T.f., extract from thyroid-fed cats ; T., extract 



from thyro-parathyroidectomised cats. The upper tracing : U represents the uterus ; 



S, the signal ; t., the time in 30-second intervals. 



Fig. 2. — Effect upon the blood pressure of a pithed cat of the intravenous injection of 2 c.c. 



of a O'OOl per cent, extract of dried pars nervosa derived from 

 T., the pituitaries of thyro-parathyroidectomised cats ; T.f., the pituitaries of thyroid-fed cats ; 

 N., the pituitaries of normal cats. B.P. is the carotid blood pressure ; ^S"., the signal and 

 zero line of blood pressure ; t., time in 10-second intervals. 



When tested by Elliott's method upon the low blood pressure of a pithed 

 cat, doses of 2 c.c. injected intravenously cause a small transient rise of 

 blood pressure, but again no appreciable difference appears in the action of 

 the three materials. The experiments were repeated and injections made in 

 diff"erent orders, but no change in the results occurred. 



