THE ADRENAL BODIES 235 



that the adrenal medulla is a chromaphil gland of a more 

 highly developed type than that of the scattered masses of 

 chromaphil cells in other regions. 



Cramer has recently come to the conclusion that an increased 

 activity of the thyroid gland leads to an increased liberation 

 of adrenin from the adrenal bodies. He has formulated the 

 conception that the thyroid and adrenal bodies form part of a 

 mechanism for the chemical heat regulation of the body. He 

 uses osmic acid vapour as a fixing agent to show the adrenin 

 granules under varying conditions. The method has been 

 applied to the adrenal bodies of mice and rats subjected to 

 the conditions which were expected to produce alteration in 

 the functional activity of the glands ; these were thyroid feed- 

 ing, thyroidectomy, injection of ^-tetrahydronaphthylamine 

 and other procedures. In all cases, he says, the method gave 

 evidence of distinct changes in the medullary cells. There was 

 evidence of the passage of adrenin granules into the blood- 

 vessels of the medulla after injection of ^-tetrahydronaphthyla- 

 mine. The granules disappear if the glands are exhausted, and, 

 in the various conditions demanding increased activity of the 

 glands, fine black granules, similar to the granules of the 

 medulla, appear in the cortex, especially in the layers of cells 

 nearest the medulla. Cramer suggests that this is evidence 

 that the cortex takes part in the functional activity of the 

 medulla and that these two parts of the gland are not two 

 physiologically independent organs. 



These observations, if confirmed, have a very important 

 bearing on the question of the relationship between cortex and 

 medulla of the adrenal bodies. Up to the present time there 

 has been no satisfactory evidence that the two portions of the 

 gland have any relation to each other, either embryological or 

 physiological. 



Even if it could be shown conclusively that under certain 

 conditions adrenin granules are found in the part of the cortex 

 next to the medulla, this would by no means prove that the 

 cortex normally takes a part in the production of adrenin. It 

 might be supposed that under pathological conditions adrenin 

 might not be able to escape by the usual channels, and so would 

 overflow into the neighbouring cortex. 



The histological evidence as to a secretory function of the 

 adrenal medulla seems to us to be far from satisfactory. 



