THE SUPRARENAL SYSTEM 281 



horse. Alexander, however, lays special emphasis upon the 

 fact that cortical granules did not stain black with osmium, but 

 that they acquired a brownish tone, and for this reason must be 

 composed of a chemical substance other than fat. 



In 1895, Kaiser! ing discovered that by far the greater number 

 of the cortical granules are double refractive to polarized light. 

 They had long been known to have a high refractivity, and Orgler, 

 who carried Kaiserling's experiments still further, gives the 

 following account of their microchemical nature. The granules 

 measure .4 to 18 microns, and have an average dimension 

 of 4 to 5 microns. They are soluble in water, readily 

 soluble in ether and chloroform, and dissolve slowly in 

 alcohol. They are unaffected by caustic soda solution, acetic 

 acid, and concentrated sulphuric acid. They stain red with 

 sudan III., at the same time losing their double refractivity. 

 When treated with osmic acid they take on a grey-black tone, 

 and if allowed to remain for a longer period in osmic acid- 

 fixing by Altmann's method, for instance they stain black. 

 Treatment with osmium, as well as fixing and hardening by other 

 methods, destroys their anisotrophy, thus their optic differenti- 

 ation from the fat-granules disappears. They are soluble in xylol, 

 chloroform, and bergamot oil, and at this stage this is the only 

 distinction between them and fat-granules treated with osmium, 

 the latter being insoluble in these reagents. Orgler concludes 

 that the cortical granules are not identical with fat ; from their 

 double refractivity, the manner in \vhich they are influenced by 

 osmium, and their resistance to acetic acid and caustic soda solu- 

 tion, he thinks it highly probable that they are related to the 

 myelin of the medullary nerve-fibres. 



The chemistry of the cortical granules was minutely investi- 

 gated by Hultgren and Andersson. These authors found that the 

 microchemical reactions of the cortical granules were in every case 

 the same as those of fat. Their greater solubility after treatment 

 with osmium is their only point of difference. Alexander showed 

 that lecithin is present in the suprarenals in large quantities, and 

 Hultgren and Andersson incline to a relationship between this 

 substance and the cortical granules, taking further into consider- 

 ation the large quantity of so-called myelin forms which appear 

 in the etheric solution after the addition of water. They W 7 ere 

 unable to demonstrate phosphorus in the cortical granules, and 

 were thus compelled to leave the question of their lecithin contents 

 unsolved. All that they could say was that the cortical granules 

 are composed of fat, but that they probably differ in certain 

 respects from the other known fats. In 1902, P. Ewald discov- 

 ered that the suprarenal cortex coloured a diffuse pale pink with 

 scarlet R., and he believed that this was due, not to fatty degener- 

 ation, but to infiltration of fat. 



Plecnik's observations (1902) are of exceptional interest. He 



