FARMERS' INSTITUTES. 297- 



The lower orders, on the other hand, which include the various parasites, 

 including the trichina, have no breathing organs, are Avithout red blood, while 

 very many have no head, no intestine, no nervous system. The reproductive 

 organs of these lower orders of worms are very highly developed, and their pro- 

 lificiiess oftimes almost beyond computation. This is true of all animals where 

 the conditions render the existence of the young very precarious. It is esti- 

 mated that the human tape \iorm.(lcBnia solium), Fig. 1, which, when mature, 

 is domiciled in the alimentary canal of our own species, will produce 35,000,- 

 000 eggs. Yet, notwithstanding this tremendous fecundity, nature has very 

 kindly made the ''struggle for life" so severe that very generally not one of these 

 myriad eggs finds opportunity to develop. 



A very strange freak in animal reproduction finds illustration among some of 

 these lowest worms, which, witli other facts, lead the evolutionist to believe that 

 plants and animals had a common ancestry. I I'cfer to reproduction by fission. 

 Nature uses growth as a knife, so to speak, by which she divides an animal, and 

 then, like a true nurseryman, she plants each part in the proper surroundings, 

 and lo ! there are two perfect animals. Nature does with these animals just 

 what she alone, or with the aid of the nurseryman, does with our vines and 

 treees. She cuts an individual asunder, and from the parts makes two as per- 

 fect as was the original. Nor with the lowest worms does this seem so strange 

 as with plants even, for they are more homogeneous. The plant has its roots, 

 its stem and its leaves — all different and for a different function. Not so the 

 worm ; each part seems a perfect f ac simile of every other part, not only in 

 structure but in purpose. So if these simplest worms are cut in two, the parts 

 have only to heal that they may be their former selves abbreviated. 



Again, some of these lower worms reproduce by a pi'ocess of budding, not 

 unlike that familiar to the botanist. A bud starts from the worm, which, by 

 growth and development soon duplicates that from which it arose, and soon, 

 instead of one worm, we have a cluster. Here, again, we have a claim to dis- 

 tant relationship with plants. This budding is illustrated in one of the most 

 fatal of human tape worms, TcBJiia ecliinococus. 



Another peculiarity among some of the parasitic worms, which is also claimed 

 by some even of the highest plants, and thus marks a distant affinity, is that 

 individuals are both male and female at the same time, and hence are what are 

 called liermaphrodites. Each individual possesses both male and female organs, 

 and self-fertilization is not only ])ossible, but imperatively necessary to rein'oduc- 

 tiou. This is true of all tape worms. The fact that all the higher groups of 

 animals often make attempts towards hermaphroditism is surely not without 

 significance. 



The wliole number of described species of parasitic worms is upwards of 2,000, 

 while more than 100 species are found in man and the domestic animals. 



To any Avho may Avisli to pursue this subject further, I Avould state that the 

 best treatises are in foreign works, and mostly in French or German, though 

 there is much in our own literature. Those AA'ho Avish for pure science Avill pro- 

 cure Dr. Packard's ''Life History of Animals;" also Dr. J. Leidy's "A Flora 

 and Fauna Avithin Living Animals," in Smithsonian contribution for 1852. 

 Those Avho prefer the more practical part of the subject Avill find a A'ery full and 

 interesting expose of the whole subject, by Prof. Verrill, in the report of the 

 Connecticut Board of Agriculture for 1869 and '70, and a less elaborate treatise 

 in the valuable work just published by Prof. James Low, "The Farmers' Vet- 

 erinary Adviser," — a work Avhich I heartily recommend to every farmer, and 



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