live in Salt'ivuter, and vice versa. 225 



M. Eeudant noted carefully llie luunber of individuals which 

 died, on the one hand, in fiesh water; and on the other, in salt 

 water : it was in this way that he ascertained the differences 

 about to be noticed. 



All the species of Ivmnaeae and planorbes, the physis of cold 

 springs; and the patella Jacustris-\\\& perfectly well in salt water. 

 In fact, in the space of hve months, there died in the fresh water 

 fifty-four of the hundred animals which had i)een kept in it, and 

 ia the salt water there died fifty-seven of the hundred; the dif- 

 ference' is scarcely worth mentioning. 



On the contrary, the other species of paludincs [helixviuipara^ 

 helix lentaculula of Limiseus), and the nerites of the Seine 

 seemed to suffer from cheir long eoutiiuiaiice in salt water, and 

 more died than in fresh water. In short, in the fresh water only 

 forty of the hundred died ; and in the salt water seventy-one of 

 the hundred died. 



All the bivalve molluscae, the anodontes, the mulettes, and the 

 cyclades, put into salt water died during the experiment, and 

 before the liquid had attained the degree of saltness which it 

 was necessary to attain. On the contrary, they lived the whole 

 summer in fresh water, and continued in it at the end of autumn. 

 It must be remarked, however, as an important result, that these 

 same species lived perfectly well in water charged with only 

 0-02 of salt. 



1\I. Beudant also resumed the experiment which he had be- 

 gun with water charged with sulphate of lime, in order to ha- 

 bituate the molluscte gradually to live in it. At first he diluted 

 with a great quantity of Seine water, the water which was 

 stroiiiily saturated with this kind of salt: afterwards he kept di- 

 luting it gradually; and lastly, he employed it completely sa- 

 turated. 'I'he molluscse at first lived very well: subsequently 

 several died, in proportion as the qiiantity of salt was increased ; 

 and lastly, the few remaining died when the saturated liquid was 

 used. This experiment repeated at two subsequent periods gave 

 the same result. 



We now come to the experiments on marine molluscse which 

 M. Beudant made in 1812 and 1813. 



He collected several individuals of various kinds of marine 

 testaceae, such as the patellae, fissarellae, crepidula?, haiiotides, 

 sabots, cerites, buccin;e, telliaes, venuses, oysters, ike. &c. 



Several individuals of the above genera, when plunged stid- 

 denly in fresh water, contracted within their shells, and died in 

 that state. Those speoies only which live habitually on rocks 

 placed out of the water lived a little longer, but they soou 

 perished also. 



M. Beudant, in order to proceed afterwards to the experiment 

 Vol. 48. No.221. StfpMSie. P proper 



