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ALFRED C. REDFIELD 



the gonads. When they are fixed in a mixture of formol and 

 Miiller's fluid and sectioned, it is found that the peripheral 

 portion is composed of alveolar masses of tissue which take on the 

 yellow stain characteristic of the medullary substance of the 

 mammalian adrenal gland. Extracts made by grinding a pair of 

 these glands in 2 cc. of physiological salt solution cause an inhibi- 

 tion of the tonic contractions of the intestine of the white rat 

 (figure C). This reaction is characteristic of adrenin (figure B) 

 Extracts made in a similar way from other tissues of the horned 



Fig. B Record of the effect of adrenin upon the rhythmic contractions of the 

 intestine of the rat. At X adrenalin chloride 1 : 100,000 in Ringer's solution was 

 introduced. At Y Ringer's solution replaced the adrenalin solution. 



Fig. C Record of the effect of an extract of the adrenal glands of the horned 

 toad (introduced at X) upon the rhythmic contractions of the intestine of the rat. 

 At Y Ringer's solution replaced the adrenal extract. 



Fig. D Record of the effect of an extract of the epididymis of the horned toad 

 (introduced at X) upon the rhythmic contractions of the intestine of the rat. At 

 Y Ringer's solution replaced the extract. 



toad, such as the liver (figure E), skeletal muscle (figure F), 

 and testis (figure G), do not produce this reaction. Extracts pre- 

 pared from the epididymis do cause an inhibition of intestinal 

 muscle (figure D), but this action is readily understood when it is 

 considered that the adrenal glands lie in immediate juxtaposition 



