554 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



tests "characteristic of the group of nucleo-albumins." We are 

 not, therefore, dealing with the group of nitrogenous fats to 

 which lecithin, the main constituent of myelin, belongs, but 

 with what probably represents, not a mere artifact, but an in- 

 dividual constituent which is precipitated by the fixing mixt- 

 ures. It is important to determine, therefore, the exact na- 

 ture of the Nissl "bodies," and perhaps by a process of exclusion 

 ascertain that of the unstainable substance. 



"Held," says Professor Barker, "undertook a most careful 

 and exact chemical study of the granules in alcohol tissues. 

 Thus, he found that the Nissl bodies are insoluble in dilute 

 and concentrated mineral acids, in acetic acid, boiling alcohol, 

 cold or boiling ether, and in chloroform. On the other hand, 

 they are easily soluble in dilute and concentrated alkalies. 

 With pepsin and hydrochloric-acid digestion he found that the 

 ground-mass of the protoplasm vanished and that the Nissl 

 bodies alone remained undigested: the reverse of what occurred 

 on treatment with an alkali. The Nissl bodies yielded no reac- 

 tion with Millon's or Adamkiewicz's reagent. Held obtained, 

 however, slightly positive results with Lilienfeld and Monti's 

 microchemical test for phosphorus, and a considerable quantity 

 of the gray matter of the spinal marrow after digestion with 

 pepsin and hydrochloric acid examined by Siegfried, of the 

 physiological laboratory of Leipzig, showed the presence of 

 phosphorus. Held concludes, however, from these various re- 

 actions, that the Nissl bodies belong to the group of the nucleo- 

 albumins: a view which agrees with the investigations of 

 Halliburton, who found in the gray matter a nucleo-albumin 

 which coagulated at from 55 to 60 C. and which contained 

 as much as 0.5 per cent, of phosphorus." 



The large proportion of phosphorus further sustains the 

 preponderating role that the oxygen of the plasma must play 

 in the neuron, owing to the activity of the reaction between 

 these two elements. It also indicates a close relationship be- 

 tween the neuron and all other cellular structures of the or- 

 ganism. Thus, referring to Held, Barker says: "He asserts 

 that in numerous experiments with his method (formol freez- 

 ing) he has found in the most different organs constituents of 

 the cell-body which behave not only tinctorially, but also mor- 



