CHAP. X.] THE NERVOUS TISSUES. 481 



shewn that the ether extract of red blood-corpuscles, besides choles- 

 terin, contained a body, the amount of phosphorus in which corresponded 

 to S'25 p.c. of P 2 O 5 (that is to say, containing 3'6 p.c. of phosphorus), 

 and which therefore could not be protagon. Hoppe-Seyler had by 

 this time obviously commenced to entertain doubts as to the existence 

 of protagon, though he did not commit himself to a denial of its 

 presence in the brain ; indeed, by implication he rather admitted his 

 belief in its existence 1 . 



Another of Professor Hoppe-Seyler's pupils, Dr Diaconow 2 , now 

 continued the investigation. 



In a paper on the bodies containing phosphorus which are present 

 in the hen's egg and in the ova of the sturgeon, he came to the 

 following conclusions : 



1. Gobley's lecithin and the phosphorized bodies which are 

 obtained from Ichthin and Vitellin yield on boiling the same products 

 of decomposition as protagon. 



2. They contain about twice as much phosphorus as protagon, 

 so that they are either altogether distinct from protagon, or they 

 consist of a mixture of protagon with a second phosphorized body. 



3. In any case protagon is not the only phosphorized proximate 

 principle of the body. 



4. The discovery of phosphoric acid in alcoholic or ethereal extracts 

 of different animal organs, does not entitle us to conclude that protagon 

 is present. 



5. The quantity of phosphoric acid found in an ethereal extract, 

 freed from cholesterin and fats, affords no estimate of the quantity of 

 protagon. 



A short time after the appearance of the preceding, Diaconow 

 published a second paper 3 in which he described the properties of 

 the phosphorized constituent of yolk of eggs, to which he correctly 

 ascribed the name which Gobley had given to it, giving the results of 

 analyses, and naming the chief products of its decomposition. 



According to Diaconow' s description of lecithin from 

 Diaconow's eggs this body has the following characters : 



f Pure lecittlin presents the appearance of a yellowish- 



white, waxy, very hygroscopic solid, which when in 

 thin layers shines with a silky lustre ; it is soluble in ether and 

 alcohol, it swells in water, and on shaking it in, or stirring it with, 

 water it forms a starch-like solution which filters with difficulty. 

 When ignited it burns away, leaving as only residue phosphoric 

 anhydride 4 . The chemical formula of the body calculated from its 



1 "Ob aber neben Protagon auch Lecithin sich in der Hirnmasse findet habe ich 

 nich untersucht." Hoppe-Seyler, Ibid. p. 220. 



2 Diaconow, " Ueber die phospborhaltigen Korper der Hiihner- nnd Htoreier" (Vor- 

 laufige Mittheilung). Hoppe-Seyler, Med.-chem. Untersuchungen, Heft 2, p. 221. 



3 Diaconow, "Ueber die chemische Constitution des Lecithin," Centralblatt fur die 

 med. Wissenschaften, 1868, No. 1, p. 2. 



4 This is a curious mistake which has been repeated by all physiological chemists ; 

 the residue is one of metaphosphoric acid. 



