330 BOARD OP AGRICULTURE. 



is thus described by Colin : "After the death of the mother its 

 body swells, its skin is torn off, and the oviducts float free, and 

 masses of eggs and myriads of embryos escaping disperse 

 themselves at the bottom of the water. I have watched for 

 eight days in succession the continuance of this hatching, the 

 little ones always showing the same vivacity alike in the 

 clearer parts of the water and in the vicinity of the detritus 

 from which they liave sprang. Whilst a certain number died, 

 there still remained a prodigious quantity, soon, however, be- 

 coming mingled with infusoria developed in the liquid." 



" There are here two facts : the birth of the worms in the 

 dead body of their mother, and the external life of the little 

 ones, the cause and condition of the contagion. In effect, 

 the animals, of which the bronchia conceal the strongyli, re- 

 ject them under the influence of cough and the expectoration 

 of mucous charged with worms, which fall on the food, the 

 litter, upon the soil, or in the water drunk ; the mothers die, 

 but the eggs are hatched, and the living brood wait till they 

 have the opportunity of entering the bodies of the animals. 

 It is, above all, in water that they are long preserved outside 

 the animal economy. I have watched them in pools of fresh 

 and stagnant water, the one destitute of vegetation, the 

 other penetrated with confervas or covered with lentiles, dead 

 leaves and divers debris. The adult worms died at the end 

 of some days. From their carcases the oviducts escaped, 

 carrying with them eggs in all stages of development. In- 

 cubation, already well advanced during life, is continued with- 

 out interruption. The embryos are expelled from the shell 

 and dispersed in the water during one, two, three, four, five, 

 or six weeks, according to the temperature and other condi- 

 tions of the liquid. The development takes place more 

 regularly in fresh water than in salt ; in river than in spring 

 water ; in pools with lentiles and conferva than in pools ex- 

 posed and slimy. It was notably retarded, but not suspended, 

 in fetid water charged with carburetted and sulphuretted 

 hydrogen". These worms are so tenacious of life that their 

 evolution takes place in the customary manner, even in water 

 in which portions of the infested lungs have been macerated. 



