198 BOVINE PATHOLOGY. 



fact that blotting-paper dipped into that fluid and dried 

 becomes '^*' touch paper/' 



A peculiar form of arsenical poisoning is known as the 

 CorPER-SMOKE Disease. It is supposed to be due to finely 

 divided arsenic spread by the copper- smelter's furnace. 

 *' Young animals are most susceptible of this influence ; 

 and among the most marked effects are a disposition to 

 ophthalmia, which in general quickly terminates in cata- 

 ract, enlargement of the knee- and hock-joints, and 

 periosteal exostosis of the bones of the extremities. The 

 first indications of animals being thus affected are dul- 

 ness and refusal of food. On examination the teeth will 

 be found incrusted with a bluish concretion, the gums 

 humid and red, and the saliva secreted in increased 

 quantities, symptoms analogous to ptyalism '' (Morton). 



Post-mortem. — It is observed that the bones are friable, 

 and have a peculiar reddish-brown colour. Such are the 

 most frequent poisons of the ox. 



Addendum 2. — Parasites and Parasitismus. 



Among the special causes of the various diseases of 

 the higher animals those which are themselves distinct 

 organisms, whether of an animal or vegetable nature, 

 demand special notice, whether it be on account of their 

 clinical importance or of the peculiar features of their 

 life-histories. 



That one animal should live inside another was at first 

 thought to be such a very strange matter that it was 

 attributed to evil agencies generating such beings de novo, 

 and it was then, and is sometimes even now, thought that 

 the presence of parasitic organisms in the body consti- 

 tutes disease. But so far from this being so, we now 

 know that large groups of animals have their typical 

 habitat within other beings, and some observers have even 

 gone so far as to attribute to the gastric infusoria of her- 

 bivora (see Fig. 27), a decidedly beneficial effect in the 

 elaboration of chyme. Far-fetched as this idea is, we can 

 well believe, that under certain circumstances animals and 



