296 STATE BOAKD OF AGKICULTUEE. 



''TRICHINA spiralis" 



was given by Prof. Cook : 



The subject of this lecture, tliough one of the minute objects of creation, 

 demanding wlien young the aid of the microscope that it may be even visible to 

 human sight, is one of exceeding interest, and of as great importance. What 

 more wonderful than that an animal so small as to be almost invisible to the 

 eye can eat, move, and even reproduce itself? What more important than the 

 knowledge that these minute animals are able to overcome even man liimself? 

 What more startling than the fact that to-day, as through all the past, these 

 same worms, seemingly so insignificant, have been engaged, all silent and un- 

 known, in their fatal work, now claiming a single victim, now snatching a whole 

 family, and anon demanding human tribute from an entire community. It is 

 indeed true that with the sharper vision, which added intelligence always gives, 

 modern research has traced to this cause some of the most terrible epidemics of 

 the past. 



The interest in this subject is still further enhanced by the fact that as yet 

 medical science has devised no cure for the attacks of this parasite. But sci- 

 ence, the great philanthropist of our time, has pointed to preventive measures. 

 And in this case, of all others, with a terrible loathsome disease as the dreaded 

 evil, prevention would be greatly preferred to cure. 



Let us, then, examine the pork-worm's place among animals, with a brief 

 notice of some of its relatives, then study its natural history, next speak of its 

 discovery, show how its continuance is secured, how and why it affects man, 

 and lastly give such practical suggestions as are of interest in the premises. 



Ihe Tridiina spiralis' Place in the Animal Kingdom. 



The pork-worm is correctly named, as it belongs to the great class of articu- 

 lated animals, — those which are made up of rings, — called worms. 



It is hard to describe this class of animals, for taken as a whole they are very 

 diverse in their peculiarities, though by studying the various individuals we find 

 affinities which lead us to establish the class. This fact that what are known 

 as natural groups of animals will not admit of a fixed and absolute definition, 

 but that animals of any group possess characters which not only seem to sepa- 

 rate them from others of their class, but also to link them to other groups, is 

 one of the facts which has led the most of our students of natural history to 

 adopt the theory of evolution as the true theory of creation. 



AVhile I may not give you a reliable definition of the class worms, I would 

 like to correct a very popular mistake in reference to the group. The only 

 worms that are familiar to you, I dare say, are the earth worms or angle worms, 

 the leeches, and perhaps the hair-worms. It is very common to call the young 

 of insects worms, as we speak of the canker worm, the tomato worm, the cur- 

 rent worm, etc. Now, true worms are always cylindrical, footless, and uniform 

 from head backwards from the egg till death. Not so with caterpillars, slugs, 

 maggots, 'and other so-called worms. These are but the first stage of the less 

 repulsive flies, or the beautiful and attractive moth or butterfly. 



The pork worm belongs to the parasitic worms, a very numerous division, and 

 so named because they subsist on the substance of other animals, on which they 

 depend even for existence. 



The independent worms are of a higher order, called annelids, some of which 

 live in the ocean, possess beautiful tufted gills, quite a complex circulation, red 

 blood, a well defined head, with eyes and mouth, and a complete alimentary 

 canal. Our common angle-worm is an annelid, but is destitute of gills. 



