THE ADRENAL BODIES 183 



Schafer adds a further suggestion viz., that the formation 

 of this substance, being once started, its amount is also con- 

 trolled by the sympathetic, and if this control be cut off an 

 inordinate quantity may accumulate, thus increasing the 

 excitability of the isolated muscle fibres. The observations 

 of Macfie (see above, p. 181) prove that the presence of 

 nerve fibres is essential to the original appearance of such 

 hypothetical excitable substance. 



These different views do not accord very well together, but 

 the fact that adrenin has functionally a very intimate relation 

 to the sympathetic nervous system is particularly interesting 

 when we remember the accepted origin of the chromaphil 

 tissues. 



According to recent observations by Langley, in all cells 

 two constituents at least must be distinguished : (1) Sub- 

 stances concerned with carrying out the chief functions of the 

 cells, such as contraction, secretion, the formation of special 

 metabolic products ; and (2) receptive substances, especially 

 liable to change, and capable of setting the chief substance in 

 action. According to this author, the active substance of the 

 adrenals produces its effects by combining with the receptive 

 substance, and not on nerve endings nor the chief substance. 

 So that in this view the controversy as to whether adrenin 

 acts on muscle itself or on sympathetic nerve endings is com- 

 promised by assuming that there is some material in cells 

 originally under control of the sympathetic, which material is 

 specially excited by adrenin. 



This theory of Langley has not, however, been universally 

 accepted. There is some evidence which tends to show 

 that after all adrenin acts directly upon the smooth muscle. 



Among the other effects of adrenin which have been noted 

 are increase of intra-ocular pressure after intravenous injection, 

 and changes in the structure and function of the kidneys. 

 Bardier and Frankel record a diminution of secretion of urine 

 owing to constriction of renal vessels after the administration of 

 adrenin. Subsequently and more significantly the conditions 

 are reversed. Adrenin mydriasis has been employed as a 

 diagnostic sign of increased diffusibility of the cornea. Adrenin 

 appears to increase the activity of ansesthetics applied locally 

 to a nerve. It is said that adrenin gives rise to increased flow 

 from the thoracic duct as long as the blood-pressure is high. 



