138 OSTRICH-FARMING IN SOUTH AFRICA. 



"tape -worm/' by directly consuming the bird's food 

 and simply depriving it of nourishment, but where 

 they act by destroying, or greatly injuring, some vital 

 organ, and thus causing a general break-down of the 

 system, as with the " Strongylus Douglassii ; " disease 

 of the kidneys, where the cause may be either a para- 

 site in them, the effect of a cold, of bad food, or other 

 causes ; a disease of the lungs said to closely resemble 

 the " lung disease " (pleuro-pneumonia), of cattle, and 

 reported to have been prevalent in the Graaf Reinet dis- 

 trict last year, but of which we have never seen a case. 



All diseases were formerly divided into two classes : 

 namely, those that were either infectious or contagious, 

 and those that were neither infectious nor contagious ; 

 the infectious being those that were spread by inhaling 

 the breath or the gases given off from the skin or stool of 

 a diseased animal, the contagious being those that were 

 spread by the contact of some absorbent gland, such as 

 the tongue, lips, or generating organs with a diseased 

 animal, or with the mucus which has come from a dis- 

 eased animal ; the others being all those that were not 

 transferable from one animal to another. But of late 

 years it has been noticed that these terms would not 

 embrace all diseases, and the name *' communicative" has 

 been applied to all those which, whilst neither infectious 

 or contagious, were capable of spreading from one animal 



