THE SYMPATHETIC SYSTEM 9 



stance secreted, and what is more important, by means of 

 physiological and experimental studies prove the action of 

 these secretions. By these means is constituted a solid 

 base for physiological, pathological and clinical deduc- 

 tions. In this respect considerable progress has been 

 made during the last few years, but there is still much to 

 be done. The study of the pathological gland goes parallel 

 with the study of the normal gland. The thyroid and the 

 suprarenal are the best known from the histological and 

 physiological point of view. They are also the two glands, 

 among those of internal secretions, whose pathology is 

 most definite. We are beginning to know the pituitary as 

 regards to its histology and physiology and it is only since 

 then that its pathology is better understood. It. is to be 

 hoped that further studies of the physiology and anatomy 

 of the endocrines will be made, which will throw further 

 light on their pathology. Already certain well-defined 

 facts have been established. 



THE HISTOLOGICAL STUDY of these glands has enabled 

 us to examine how the glands work. Not only can we 

 study the thyroid vesicles, for instance, and see how the 

 gland secretes a colloidal substance, which is re-absorbed 

 by the blood vessels surrounding the epithelum but we 

 can, thanks to the modern methods, delicately stain 

 the cellular protoplasm and see the glandular cell in 

 activity. In the case of the liver, fill with glycogen, or 

 suprarenalin, in the case of the medullary cells of the 

 suprarenal capsule. In this respect, the researches of 

 Henle are very suggestive. He has opposed the chromaf- 

 fin, or suprarenalin cells to the cells with collesterin or 

 nerve cells. Very significant are also the histological in- 

 vestigations on the acidophils, basophils, cyanophils, 

 chromophobes cells of the pituitary, notably the work 

 done on the pars intermedia, at the junction of the anterior 



