587 



observation of such attractions and repulsions in one of the animal 

 tissues. 



The paper continues with an account of an experimental inves- 

 tigation into the effects of irritants upon this function of the pigment- 

 ary system. Many experiments are related, all tending to support 

 the general proposition, that "all agents, without any exception, 

 which have the power of inducing accumulation of corpuscles and 

 stagnation in the blood-vessels when applied to the web, paralyse at 

 the same time the functions of the pigment-cells." It is also shown, 

 from experiments upon amputated limbs free from blood, that this 

 effect is independent of the state of the circulation. In cases of 

 slight irritation, in which the blood resumes, after awhile, its natural 

 characters (re-solution taking place), the paralysis of the pigment- 

 cells is only temporary. " Thus the pigmentary system of the frog 

 is a remarkably sensitive index of the condition of the affected tissue, 

 and it is fortunate that its physical characters render it so easy to 



read its pointings The only other tissue of the frog's web, the 



functions of which can be observed by the eye, is that of the arterial 

 muscular fibre-cells," and it is found that arteries passing through 

 an inflamed area lose their power of contraction within the limits of 

 that area, whereas the same vessels may be often seen to contract in 

 other parts of their course. 



" Thus, direct observation of the structures of the frog's web 

 which discharge functions apparent to the eye, furnishes unequivocal 

 support to the inference derived from other considerations, that in 

 inflammation the tissues of the part, the primary seat of the affec- 

 tion, are in a state of diminished functional activity." 



The "conclusion" consists of an inquiry how far the views ex- 

 pressed in the paper regarding the early stages of inflammation 

 harmonize with the more advanced phenomena of the morbid pro- 

 cess and with other facts of pathology. 



VOL. VIII. 2 U 



