NEMATODA. 767 



The professional importance of tlie trichina more directly 

 concerns the medical man than the veterinarian ; nevertheless, 

 since the human disorder termed trichiniasis takes its origin from 

 the consumption of animal food, especially pork, it is clearly the 

 duty of the latter to understand the nature of the malady thus 

 provoked, and to acq^uaint himself with the phenomena of the 

 parasite's development. The experiments of various helmintho- 

 logists, and especially those of Davaine, have distinctly proved 

 that when small animals, such as rats, rabbits, and cats, are 

 largely infected, they, like man himself, readily succumb to the 

 disease. In the case of larger animals, a very great amount of 

 infection is necessary to give rise to any external symptoms. 

 So complete, indeed, does this immunity appear to be, that a pig 

 experimented on at the Eoyal Veterinary College showed no sign 

 of the disorder, although from subsequent post mortem evidences 

 it was calculated that its flesh contained sixteen millions of 

 living worms. 



Until very lately we flattered ourselves that in England and 

 Scotland there was no such thing as trichina existing in our 

 home-reared porkers ; but so far as the former division of the 

 country is concerned, this immunity can no longer be said to 

 exist. Not only have several English fed pigs been found to 

 harbour spiral flesh-worms, but in the year 1871, as recorded by 

 Dr. Dickenson, an outbreak of trichiniasis occurred in a farmer's 

 family in Cumberland, this attack resulting from the consump- 

 tion of pork reared by themselves. As ]\Ir. Gamgee has well 

 remarked, " If pigs are permitted to swallow the germs of human 

 parasites, as in Ireland and in many British piggeries, we must 

 expect hams, bacon, and pork sausages to be charged with the 

 embryonic forms of human entozoa." Very much more, of 

 course, might be said on this subject in relation to questions 

 of hygiene ; but our object in these pages is merely to show the 

 necessity of a general acquaintance with the subject. 



The symptoms, whether occurring in man or animals, are 

 generally believed to be due to the wounds and consequent 

 irritation set up by the worms during their wanderings in tlie 

 tissues of the liost ; but whilst this is true as a cause of the 

 phenomena occurring in the second stage of the disease, it is 

 oljvious that the earliest symptoms, often accompanied with 

 diarrhoea, are due to intestinal irritation alone. Some authors 



