556 Messrs. G. A. Buckmaster and J. A. Gardner. [Mar. 7, 



is modified as the anaesthetic state progresses to asphyxia, owing to the 

 increasing feebleness of the respiratory centres or to the gradual effect of the 

 drug on the muscles concerned in respiration, a factor which probably is of 

 small importance, since Sherrington has shown that striped muscles, unlike 

 the heart, are not readily poisoned by chloroform. In the case of cats, 

 during the very early stages of anaesthesia by chloroform, the rate of 

 respiration diminishes, and is followed by a marked increase. This variation 

 of respiratory movement would no doubt affect the relative proportions of B 

 and C. Of the chloroform passing inwards by the pulmonary epithelium 

 and which is carried by the blood, part is associated by the cells, D, and a 

 part is eliminated, E. As anaesthesia progresses D will be a decreasing factor, 

 while E will be an increasing factor, owing to the augmentation of chloroform 

 in the blood returning to the lungs. The rate of elimination, E, may be even 

 greater than the rate of assumption, C, though the total amount of C exceed 

 that present in the returning blood. Although the rate at which chloroform is 

 tending to pass out may be greater than the rate at which it tends to pass in, 

 the actual amounts going either way will depend, other things being equal, on 

 the mass of the chloroform on either side of the pulmonary epithelium. If, 

 therefore, the nerve centres remained unaffected, we should expect that with 

 a constant normal type of respiration a condition of equilibrium would 

 be reached between factors A and B and C and E, with any given percentage 

 of chloroform inhaled, which would effect a perfect anaesthesia and not 

 rapidly kill. 



During the progress of anaesthesia the nerve centres become paralysed, but 

 not necessarily in a regular order, as we have often noticed that various 

 reflexes vanish or reappear in different sequence in animals of the same 

 species. We should expect, therefore, that the curves indicating the 

 variations of the percentage of chloroform in blood with time would not 

 necessarily be smooth. 



The determination of the amount of chloroform which is present in the 

 anaesthetised animal has been attempted in three different ways : (1) By 

 ascertaining the percentage of chloroform in the blood of animals anaesthetised 

 or killed by chloroform. (2) By determination of the amount of chloroform 

 in the blood and various organs of the body post mortem* (3) More 

 frequently by reckoning the difference between the amount of chloroform in the 

 inspired and expired air. Waller,! Vernon HarcourtJ Collingwood,§ and 



* Nicloux, ' Comptes Rend.,' 1906, vol. 60, p. 206. 



t Waller, ' Lancet,' November 28, 1903. 



% Harcourt, ' Brit. Med. Journ.,' June, 1906. 



§ Collingwood, ' Physiol. Soc. Proc.,' vol. 28, 1905. 



