438 THUDICHUM'S RESEARCHES. . [BOOK i. 



of their substance, and according to these differences must be divided into 

 sub-groups. "We thus obtain the sub-groups of the kephalines, myelines, and 

 lecithines. 



" Of these the kephaline sub-group, itself hitherto unknown, includes 

 members which contain the nitrogen in either one or two forms, one being 

 either choline or neurine, another hitherto unknown; and they contain 

 the fatty acid radicles also in forms with which chemistry is at present 

 unacquainted, and the members of this sub-group further vary in the 

 amount of oxygen which they contain in a manner so as to be sharply 

 characterised thereby. This variability of the constituent oxygen may 

 be transitional, but must not be confounded with that remarkable 

 reaction of the bodies of this group which I describe as their oxy dis- 

 ability. 



" The myeline sub-group, also new, contains the nitrogen in two forms, 

 of which one is choline, the other amide in a fatty acid radicle. The 

 fatty acid radicles vary, and are mostly new forms, some known forms. 

 The members of this group consequently vary in carbon, hydrogen and 

 oxygen; little in nitrogen, never in phosphorus. They are not oxy- 

 disable after the manner of kephaline, though there is an oxy-myeline 

 after the mariner of oxy-kephaline. They are the least soluble of the 

 entire group, the least decomposable, and stand the highest temperatures, 

 being unchanged by fusion at a heat above the boiling point of water. 



" The lecithine sub-group, well known from the chemistry of eggs, is 

 only with difficulty evolved from the brain, on account not only of the 

 many stages of the processes necessary for their isolation, but also on 

 account of a prominent feature of its members, namely, their readiness 

 to decompose when in the anhydrous state. This tendency to apparently 

 spontaneous lysis into proximate nuclei prevents the inquirer fixing 

 properties and varieties with the same precision as in the previous 

 groups; but it furnishes a valuable key to the explanation of many 

 changes in the sick body, which may arise, or have been proved to 

 arise, from their decomposition. 



" The chemical characteristics of these sub-groups may be summarized 

 thus : the kephalines possess the tendency to be oxydised, oxydisability ; 

 the myelines are not easily changed by any agent or influence, and possess 

 therefore stability; the lecithines easily fall to pieces, they are afflicted 

 with lability. 



"In language more technically chemical: the kephalines have on the 

 outside of their molecules free affinities for oxygen; this gas they bind 

 in several ways; when the oxygen combined with a molecule has 

 attained a certain quantity, the avidity (intensity of affinity) of the 

 molecule increases to this extent, that it monopolises all available 

 oxygen to itself until the limits of its oxydisability (at present unknown) 

 are attained ; until its free affinities are satisfied. Until then the rest of 

 the molecules, if the supply of oxygen be insufficient to oxydise all to 

 the same point, are not oxydised. The kephalines, however, are not in 

 a state of atomic tension, and therefore do not fall to pieces so easily as 

 the lecithines, but require for lysis the influence continued for some 

 time, of powerful extraneous affinities in the presence of water and heat. 



"The myelines have no apparent free affinities for oxygen; they are 

 not affected by heat to and above boiling water except to the extent of 



