CllAYFISHES AND PIGS. 45 



collected in vast numbers, and sold for medicinal 

 pm-poses as a remedy against the stone, among other 

 diseases. Their real utility, inasmuch as they consist 

 almost entirely of carbonate of lime, with a little phos- 

 phate of lime and animal matter, is much the same as 

 that of chalk, or carbonate of magnesia. It was, for- 

 merly, a current belief that crayfishes grow poor at the 

 time of new moon, and fat at that of full moon ; and, 

 perhaps, there may be some foundation for the notion, 

 considering the nocturnal habits of the animals. Van 

 Helmont, a great dealer in wonders, is responsible for 

 the story that, in Brandenburg, where there is a great 

 abundance of crayfishes, the dealers were obliged to 

 transport them to market by night, lest a pig should 

 run under the cart. For if such a misfortune should 

 happen, every crayfish would be found dead in the 

 morning: '* Tam exitialis est porcus cancro." Another 

 author improves the story, by declaring that the steam 

 of a pig-stye, or of a herd of swine, is instantaneously 

 fatal to crayfish. On the other hand, the smell of 

 putrifying crayfish, which is undoubtedly of the strongest^ 

 was said to drive even moles out of their burrows. 



