Queries and AnswerL 



20' 



each joint, if broken off, became a complete worm ; but it is now acertainedi 

 that, when this is the case, the portion is expelled : but, if a living head be 

 attached to one or more segments, the animal grows to its usual length by 

 the addition of new joints. Domestic animals are equally subject to the 

 attacks of the different species of Y'se^nia. 



I do not wonder at the supposition of some of the ancient naturalists, 

 that the intestinal worms and hydatids were engendered spontaneously ; 

 so difficult does it appear to account satisfactorily for their reproduction. 

 It is, however, now ascertained not only that the greater part produce ova 

 or living young; but that many have separate sexes, and couple as ordinary 

 animals. The hydatids sometimes are found alone in cysts, and sometimes 

 in society, and many groups in various parts of the body, as the liver, the 

 brain, the eyes, and even penetrating the heart. [See 

 p. 99.] How minute must be their ova, to pass through 

 the small tubes of the various structures of living 

 bodies, and lodge in the small ramifications of the liver, 

 brain, &c. ! Worms and hydatids, it appears certain, 

 have their sexual organs either united in each individual. 



/ 



A, The lower part of the trachea of a phea- 

 sant cut open. 



a and [>, Branches to the right and left lungs. 



c. Worms of a blood-red colour attached to 

 the inner surface of the trachea, by two 

 heads or suckers, varying in length from 

 one fourth of an inch to an inch. 



d, Cone-shaped tubercles, in which the heads 

 of some of the worms are inserted. 



B, A worm of the natural size. 



c. The same magnified when in water. 



e. Variously marked. The lower part similar 

 to the convolutions of the bowels, of a light 

 yellow colour, with streaks of blood-red. 



/, The head or sucker, surrounded on the 

 edge with a transparent horn-like subl 

 stance. 



g. In the middle is a dark-brown, somewhat 

 transparent, line, with convolutions differ- 

 ent from e. 



h. The head. Its sucker is smaller than/. 



or separate sexes; however, they produce ova, which ova are 

 circulated with the blood, and communicated to the child in 

 utero by the mother as well as the eggs during their progress 

 of formation, and develope themselves in various parts of the 

 body. How long they are before they develope themselves I 

 cannot say, nor the duration of the existence either of worms 

 or hydatids : as they have been found both in old and young 

 animals, their developement I think depends upon some favourable state of 

 the constitution, from disease or derangement of some of its organs. 



Birds are also liable to the depredation of worms and hydatids. A 

 short time since, a farmer, who is in the habit of breeding many domestic 

 fowls, had several died in a singular manner. They appeared affected 



