452 E. WACE CARLIER 



pointed out by me ('), in which the zymogen is arranged in distinct granules 

 in the cytoplasm, whilst in the rats liver it appears diffused in the form of 

 a mist with condensations hère and there, but I do not think that this 

 offers a valid objection to my argument. 



In this research I hâve presumed that the exhaustion and repair of the 

 nuclei with révélation of phosphorous and iron holding material in the 

 cytoplasm as described by Me Callum and myself in the newt's stomach 

 cells is sufficient évidence of the production of zymogen especially when 

 taken along with the discovery by Pawlow ( 2 ) of abundance of ferment in 

 the bile. 



2. The first sécrétion of zymogen by the liver cells occurs within 

 fifteen minutes of the commencement of a meal, it is purely psychic in 

 origin and perhaps reflex in character; the afférent nerve would appear to 

 be the olfactory and the efferent is probably the vagus. This sécrétion 

 varies in intensity and duration with the appetite manifested by the 

 animais, being copious with mixed and proteid diets of which they are very 

 fond, and scanty when fats and carbohydrates are given them. In this 

 respect the liver corresponds exactly with the peptic and salivary glands as 

 described by Pawlow, and it may be that the vagus carries the ferment 

 secretory nerves to it. Perhaps section of ail the nerves entering the liver, 

 though it does not effect the output of bile, would prevent the production 

 of ferments by the cells; this unfortunately through no fault of my own, 

 I hâve not been able to put to the proof. 



3. The second period of sécrétion commences in about an hour after 

 complète recovery from the effects of psychic stimulation, and it is at its 

 height somewhere between the 5 tb and the 6 th hour after feeding. This may 

 also be a reflex phenomenon, but what the afférent channel may be and 

 how exactly it is excited is at présent undetermined; the stimulus may 

 arise either from the stomach or from the duodénum. It must however be 

 born in mind that the second stimulus to sécrétion may be entirely non 

 nervous as in the pancréas which is stimulated to part with its ferments by 

 chemical means as discovered by Baylis and Starling( 3 ), perhaps secretin 

 may act on the liver cells as well as on those ofthe pancréas; to détermine 



(') Carlier : Ibid ; La Cellule. 

 C) Pawlow : Ibid. 



( 3 ) Baylis and Starling : The meckanism of panercatic sécrétion; Proc. Roy. Soc. Lond., 

 1902; Journ. Anat. and Physiol., 1902. 



