298 CIRCULATION. 



increased, that we can hardly distinguish the form of the 

 corpuscles. 1 



Influence of Direct Irritation upon the Capillary Circu- 

 lation. Experimental researches on the effects of direct irri- 

 tation of the capillaries, in parts where the circulation can 

 be observed microscopically, have been quite numerous since 

 Thompson studied the effects of saline solutions on the web 

 of the frog's foot in 3 813. a The most noticeable papers on 

 this subject are those of Dr. Wilson Philip 3 and Mr. Wharton 

 Jones. 4 The latter paper, which received the Astley Cooper 

 prize for 1850, is based on very extended and carefully 

 conducted observations, in which the author, by means of 

 various irritants, succeeded in producing very curious and 

 interesting phenomena, which he regarded as inflammatory. 

 It is not our object to discuss the nature of inflammation, or 

 to treat of the changes in the character of the capillary circu- 

 lation which are supposed to attend this condition, as this 

 subject is eminently pathological ; but it must be remember- 

 ed, in considering the effects of direct irritation on the capil- 

 lary circulation, that the phenomena thus observed in cold- 

 blooded animals cannot be taken as absolutely representing 

 the characters of inflammation in the human subject. When 

 an irritation is applied to a transparent part, the phenomena 

 observed may be due to many causes, as the direct effects 

 upon the contractile elements of the blood-vessels, the reflex 

 action through the nervous system, and the direct influence 

 of the application upon the constitution of the blood. Saline 

 or other fluids are competent to modify, to a very consider- 

 able extent, the composition of the blood, separated from it 

 only by the thin, permeable walls of the vessels ; and the 



1 POISEUILLE, op. tit., p. 158 et seq. 



2 THOMPSON, Lectures on Inflammation, Edinburgh, 1813. 

 s Medico- Chirurgical Transactions, 1823, vol. xii. 



4 Guy's Hospital Reports, vol. vii., 1851, On the State of the Blood and the 

 Blood-vessels in Inflammation, ascertained by Experiments, Injections, and Obser- 

 vations by the Microscope, by T. WUARTON JONES, F. R. S. 



