208 UTILIZATION OF MINUTE LIFE. 



To give some idea to what extent the breeding 

 of this worm is practised in France, I may state 

 here that a single leech-swamp in La Gironde yields, 

 on an average, a return dividend of fifteen per cent. ! 

 Not long ago a similar marsh in the same district, 

 and about 120 acres in dimension, sold for 10,000 

 sterling ! I learn, moreover, from very reliable 

 sources, that considerable fortunes have been realized 

 in the neighbourhood of Bordeaux by breeding 

 leeches. 



But the day cannot be far off when all these 

 leech-ponds will be dried up, and when the old 

 barbarous practice of bleeding with leeches will be 

 banished from a more enlightened medical gene- 

 ration. Then, indeed, will the useless cruelty of the 

 leech-ponds vanish for ever, and no more old women 

 or children shall be bled to death. 



Some persons have attempted to convert the 

 common leech into a barometer (Fig. 25). Among 



FIG. 25. Leech barometer. 



other curious habits it has been observed, that on 

 the approach of a tempest the animal ceases to be 



