INTESTINAL WORMS. 



127 



Round Worm (Ascaris lumbricoides), so frequently found 

 in children, is a familiar example. Professor Owen gives 

 some curious details of the fertility of this species, which 

 might well terrify us,* but for the reflection with which he 

 subsequently consoles us. " The ova are arranged in 

 the ovarian and uterine tubes, like the flowers of the 

 plantago, around a central stem or rachis. There are 

 fifty in each circle — that is to say, you might count fifty 

 ova in every transverse section of the tube. Now the 

 thickness of each ovum is ^th of a line, so that, in' the 

 length of one line, there are 500 wreaths of 50 eggs each, or 

 25,000 eggs ! The length of each division, or horn of the 

 uterus, is 16 feet or 2304 lines, which for the two horns 

 give a length of 4608 lines. The eggs, however, gradually 

 increase in size, so as to attain the thickness of goth of a 

 line : we, therefore, have at the lower end of the horn sixty 

 wreaths of ova in the extent of one line. The average 

 number through the whole of the extraordinary extent of 

 the tube may be taken at 14,000 ova in each line, which 

 gives sixty-four millions of ova in the mature female Ascaris 

 lumbricoides ! 



" The embryo is not developed within the body in this 

 species ; the ova may be discharged by millions, and most 

 of them must, in large cities, be carried into streams of 

 water. An extremely small proportion is ever likely to 

 be again introduced into the alimentary canal of that 

 species of animal which can afford it an appropriate habi- 

 tat. The remainder of the germs doubtless serve as food 

 to numerous minute inhabitants of the water; and the 

 prolific Entozoa may thus serve these little creatures in 

 the same relation, as the fruitful Cerealia in the vegetable 



