54 



Dr. H. M. Kyle. On the Action of the [June 25, 



or no effect on the intestinal canal of the higher animals, it has also 

 none on that of the fishes, as the following experiment showed. 

 Several trout were set apart in a separate tank by themselves and 

 fed for 6 weeks on boiled mussels, which had been steeped for some 

 time in the Spurge-extract. The extract employed was the ordinary 

 aqueous preparation, containing therefore a certain amount of the 

 volatile substance, and fatal to the trout when immersed bodily into 

 a small proportion of it in water. Yet when taken into the alimentary 

 canal, through the mussel as medium, it had no apparent effect — the 

 trout living upon the food appeared as active and as healthy at the 

 end of 6 weeks as those in the neighbouring tank, which had been 

 fed upon the ordinary boiled mussel. There could be no doubt that 

 the fish really absorbed some of the extract, because the mussels were 

 so thoroughly steeped in the extract that some of it must have 

 remained unchanged in their tissues ; and again the trout were kept 

 in a half -starved condition, so that when fed they eagerly grabbed the 

 mussel before it had been more than a second or two in the water. 

 There was no time therefore for the extract to diffuse out into the 

 water, and it must consequently have been ingested. 



Not only does the aqueous extract of the Spurge — with which we 

 are mostly concerned — seem to have no action on the alimentary 

 canal in moderate quantities, it also seems incapable of being absorbed 

 from the skin, or if absorbed is not fatal. Several toads which were 

 immersed for 7 days in an aqueous extract, but so that their heads 

 and necks were above the surface and the animals were thus able 

 to breathe freely, were alive at the end of that time and able to 

 respond to stimuli. This extract had been freshly prepared, and pro- 

 duced certain characteristic effects on the vascular system to be 

 presently described. What happened in the case of the toads can 

 readily be inferred from the known action of tannic acid. The 

 peripheral circulation would be affected, and the skin might indeed 

 be " tanned " to a certain extent, but this would protect the internal 

 organs from harm, and evidently did so whilst the toads were im- 

 mersed in the solution. 



From the foregoing series of observations, it might be inferred 

 that the action of the aqueous Spurge-extract is mainly local, and the 

 following experiments seem to decide conclusively in favour of this 

 inference. The gastrocnemius muscle of pithed frogs gave the normal 

 responses to stimuli, both when irrigated directly by the extract 

 and when the latter had been previously injected into the lymph. 

 The heart of a pithed toad when irrigated by the extract, as well as 

 after injection into the lymph, varied as little from its normal beating 

 as it did when irrigated by normal saline solution. These experiments 

 were performed both with the fresh extract and with the extract some 

 days old, and it may clearly be inferred that the aqueous Spurge- 



