556 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



moved. Protagon readily breaks up into its constituents. 

 Howell states that, "while protagon seems to be regarded as 

 the principal form in which lecithin occurs in the brain, simple 

 lecithin is believed to be present in the nerves and other or- 

 gans/' and he refers to Noll, 45 who found "the quantity of 

 protagon in the spinal cord may amount to 25 per cent, of 

 the dry solids; in the brain, to 22 per cent.; and in the sciatic 

 nerve, to 7.5 per cent/' That it is difficult to analyze this 

 question is suggested by his closing remark: "Regarding the 

 synthesis of lecithin in the body, or the physiological im- 

 portance of the substance, nothing is known." We have seen 

 the important role that it probably plays as myelin; its pres- 

 ence in such large quantities, as a constituent of protagon, in 

 the cerebro-spinal system plainly points to it as of the unstain- 

 able ground-substance of the neuron. 



What is the role of cerebrin, which, with lecithin, forms 

 protagon, and from which it is readily separated? In a study 

 of the chemistry of nerve-degeneration Halliburton and Mott 46 

 refer to the fact that they had previously shown that in general 

 paralysis of the insane "the marked degeneration that occurs 

 in the brain is accompanied by the passing of products of de- 

 generation into the spinal fluid. Of these," say the authors, 

 "nucleo-proteid and cholin are those which can be most readily 

 detected. Cholin can also be found in the blood." Having 

 continued this work, they now find "that this is not peculiar 

 to the disease just mentioned, but that in various other de- 

 generative nervous diseases (combined sclerosis, disseminated 

 sclerosis, alcoholic neuritis, beriberi) cholin can be also de- 

 tected in the blood." The tests that they employed were 

 mainly two: (1) "the obtaining of the characteristic octahedral 

 crystals of the platinum double salt from the alcoholic extract 

 of the blood"; (2) a physiological test and a very interesting 

 one, we may add, if the functions of the suprarenal system 

 are included in the process, namely: "the lowering of blood- 

 pressure," which the authors consider as "partly cardiac in 

 origin and partly due to dilation of peripheral vessels," and 



"Noll: Zeitschrift fiir physiol. Chemie, Bd. xxvii, S. 370, 1899. 

 * Halliburton and Mott: Journal of Physiology, Feb. 28, 1901. 



