The Difjestwe Orr/ans in Young Sheep. 641 



lung, talcing the smallest possible quantity on tlio point of a scalpel, 

 just sufficient to soil a piece of glass, you will see, in a space of the 

 size of a drop of water, millions of eggs just hatched ; and if you 

 examine an old worm, you will see eggs in all stages of development ; 

 so that she brings forth her young in a living form, and also in the 

 form of eggs more or less mature. Now, one worm will produce — if 

 I were to use figures here I should have to speak of billions, and even 

 of trillions — an immense number of eggs, and we can therefore easily 

 understand how avast amount of mischief may be done, even by one or 

 two worms. But now the question arises, Hov/ did this one worm get 

 there ? Where does the parent worm come from ? We must repudiate 

 the theory of fortuitous generation. I no more believe in the fortuitous 

 generation of a worm, or of the lowest form of animal life, than I believe 

 in the spontaneous origin of myself. We must look for other causes. 

 And here we have opened to us a vast field of investigation as yet scarcely 

 entered upon. I have experimented again and again with this class of 

 worms, which are designated by the name of nematoid or hollow 

 worms, and in every experiment I have failed to produce them within 

 the windpipe. I would, then, throw it out as a probable cause of their 

 existence, that a great number of the ova are expelled in the coughing 

 of the sheep with the mucus which is coughed up. Large numbers 

 are, I believe, expelled at each coughing, mingled with the mucous ; 

 and I would just hint at it, as a probable thing, that these ova come to 

 maturity to some extent externally to the sheep ; that certain plants — 

 it may be ordinary grasses — become the habitat of these creatures in 

 an immature form, and that in this condition they are taken into the 

 organisation of the sheep, and as each entozoon has its own particular 

 locale, these creatures very soon find their way into the windpipe, and 

 a very few doing so are productive of immense mischief. Now, I am 

 inclined to believe that this is really the means by which their pre- 

 sence is to be accounted for. We cannot for a moment suppose that 

 all the worms which we meet in the lungs, for example, under circum- 

 stances of this kind, can have entered from without. We cannot sup- 

 pose the explanation to be that the ova floating in the atmosphere are, 

 after they have become somewhat dry, received into the respiratory 

 organs, and there become matured. There are some things which 

 appear to me to militate strongly against that view of the matter. I 

 have, for example, broken up many old worms when yet alive, and 

 having thus procured eggs in various stages of development, I have 

 placed them in different kinds of fluid, none of which could interfere 

 with their vitality, and have in this manner brought them in contact 

 with the nostrils of sheep. Not only have I done that, but I have used 

 a thick mucus, like gum-water, putting into it a number of living 

 worms, as well as a large number of ova, and have administered this 

 very slowly to sheep, so that it might hang round the mouth, and the 

 worms might travel down the windpipe ; but, singular to relate, in all 

 these experiments I have failed. Knowing that )iomatoid worms are 

 perfected to a certain extent out of the organism, I have been led to 

 the conclusion that it is not improbable— I do not say it is positively 

 the case— that the ova themselves are the real cause of the mischief ; 



