412 GIRTANNER. [BOOK I. 



inflating the lungs, not with common air used again and again, but 

 with fresh supplies of dephlogisticated air? If dephlogisticated air 

 supports the name of a taper with a splendour hardly credible by 

 those who have not witnessed the experiment, is it not clearly 

 indicated as peculiarly fitted for restoring the vital spark when 

 nearly extinguished ? 



The theory thus suggested soon received a remarkable amplifica- 

 tion in the hands of Girtanner 1 . In an essay, exhibiting great re- 

 search (but at the same time shewing that a restless desire to have an 

 answer of some kind to his questions had led its author to content 

 himself with mere specious explanations), the principle of irritability 

 is identified with oxygen. All organized parts, whether of the animal 

 or vegetable kingdom, are considered to be capable of irritability, 

 and the irritable fibre is one and the same in nature wherever 

 found. Even the fluids of the body exhibit an irritable contraction 

 (i.e. coagulation) and obey the general laws of irritability. The prin- 

 ciple of irritability, or oxygen, is received by the blood in the lungs, 

 and conveyed to all parts of the body, where it is stored up in the 

 irritable fibres. There is a normal quantity for each fibre, upon which 

 its tone depends ; and the normal is preserved by the ceaseless action 

 of habitual stimuli, such as heat, light, nourishment, circulation of the 

 juices, etc. which withdraw the surplus. Thus the health of the fibre 

 depends upon an even balance of gains and losses of oxygen. If the 

 gains are excessive, irritability becomes increased. If the losses are 

 excessive through the extraordinary action of the habitual stimuli, 

 irritability sinks or disappears altogether. All reagents which are 

 thought to be capable of acting upon irritable fibres are divided into 

 three classes according as their affinity for oxygen is greater than, equal 

 to, or less than, that of the fibres. The former abstract oxygen from 

 the fibres and depress their irritability : such are opium, alcohol, fat. 

 The latter impart oxygen to the fibres, producing a super-irritability 

 which is often extremely fatal : white oxide of arsenic, Vacide muria- 

 tique oxigene, are eminent examples of this class. The intermediate 

 class behave as neutral bodies, until change of temperature, or some 

 other condition, removes them into the first class or the third. Thus 

 irritability is always in proportion to the oxygen which an irritable 

 organ or fibre contains; and whatever augments or diminishes the 

 oxygen of the body likewise augments or diminishes its irritability. 



Whether Girtanner had ever read Fothergiil's Hints does not 

 appear, nor is it of importance to enquire ; but it is certain that 

 Fothergill, four years after the publication of Girtanner's Memoirs, 

 expanded his original conception into a theory of irritability which is 

 practically identical with Girtanner's 2 . Vitality, in his view, consists 



1 Girtanner, "Me'moires sur 1'Irritabilite, considered comme principe de vie dans la 

 Nature organisee." Observations sur la Physique, ed. by Rozier and de la Metlierie. 

 1790, Vol. xxxvi. p. 422; Vol. xxxvn. p. 139. 



2 A. Fothergill, On the Suspension of Vital Action, Bath, 1795, p. 67 and else- 

 where. This Essay gained the Gold Medal of the Eoyal Humane Society in 1794. 



