ENTOZOA. 79 



why that immense complication and extent of the organs for the pro- 

 duction of normal fertile ova ? 



" The division of the body into joints is intended," Professor 

 Eschricht observes, " to produce a corresponding number of bunches 

 of ova, just as the repeated ramification of plants is destined to 

 provide space for the production of new bunches of seeds." The head 

 of the tapeworm is fixed to the mucous surface, and thence it may 

 derive the nutritive juices required for the whole organism, in a 

 degree analogous to that in which the root procures the nourishment 

 of the plant from the soil ; and the analogy of the extent to which a 

 plant is nourished by its leaf-pores may also be carried out by the 

 extent to which the tapeworm is supplied by the absorbent action of 

 its mucous integument. The ova having reached maturity, the joints 

 rupture to liberate them; or the whole joint will be thrown off in 

 the same way as the seeds of plants are freed, sometimes one by one, 

 sometimes in masses, according to the particular manner of life 

 assigned to every species of plant. " And is there any one," asks 

 Dr. Eschricht, " who, upon the contemplation of this wonderful 

 apparatus, and the extraordinary results of its agency, can for a 

 moment imagine that it is without an object or an end?" 



The geographical distribution of the human Cestoidea is, likewise, 

 opposed to the doctrine of their spontaneous origin. The organic 

 particles, or alimentary mucus of a Swiss and Dutchman, are not so 

 distinct in their nature as to account for the difference in their 

 tapeworms. Yet no Swiss that never left his native mountains ever 

 had a TcBiiia solium, and no Dutchman, the constant resident of his 

 swamps, ever had a Bothriocephalus latus. But a native of either of 

 these countries may be infested by the tapeworm peculiar to another 

 region, if he sojourn there, just as the English sailor may be attacked 

 by the Guinea-worm, if he visits the tropical regions where that 

 entozoon is common. 



The great anatomist Soemmering suffered from a Bothriocephalus 

 latus. Now he was a German ; but it was ascertained that he paid 

 occasional visits to a friend in Switzerland. There, doubtless, the 

 larvae of the parasitic worm was introduced into his body. The 

 countless ova of the tsenige, with their hard crusts or shells, and 

 tenacity of latent life, are, doubtless, widely dispersed ; the larvae are 

 early provided with express organs for attaching themselves to the 

 animals and tissues suitable for their first phase of existence, and 

 these nursing animals serve as food for the higher species destined, in 

 their turn, to subserve the complete development of the migratory 

 parasites. 



