7f)2 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



artificial elements the mussel resists less than theveuuses; and amon^ 

 these latter the reticulated venus or clovisse shows less resistance than 

 the palourde {Venus decussafa), which exhibits a remarkable degree of 

 resistance. In the solution of sulphate of magnesia, for instance, the 

 mussel succumbed after ten days, the reticulated veuus-shell after fifteen, 

 whilst the palourde was still alive after sixty days. These i)roportions 

 were very nearly maintained in the other solutions relatively to the 

 duration of life in these meduims. 



Below is given the result of these experiments as regards the palourdes 

 {Venus decussata). Five specimensof this kind were on the 10th Janu- 

 ary, 1882, placed, under the same conditions, in each of the diftereut 

 solutions mentioned above. The same care was bestowed on all of them, 

 and they were properly aerated every day. At the same time a certain 

 number of these mollusks were placed, near to the former, in vessels 

 containing natural sea- water. 

 January 10. Experiments commenced with the palourdes. 



25. They succumbed in the ioduret of potassium. 

 February 10. They succumbed in the chloride of potassium. 



15. They succumbed in the air. 



18. They succumbed in the sulphate of potassium. 



18, They succumbed in the common water. 



20, They succumbed in the solution No. 10. 



20. They succumbed in the bromide of potassium. 



20, They succumbed in the chloride of magnesium. 



25. They succumbed in the Vichy water. 



22. They succumbed in the chloride of sodium, 



22. They succumbed in the solution No. 12. 



24. They succumbed in the solution No. 0. 

 March 10. They succumbed in the sulphate of magnesia. 



10. They succumbed iu the solution No. 11. 



15. Some palourdes are still living in the 8ulx>hate of soda. 



15. The palourdes placed in the sea-water are alive. 

 Observation^ on these facts. — It a])pears from these experi- 

 ments that, in spite of the possibility of shutting thems Ives up between 

 their valves, the venuses yield to the action of the surrounding mediums, 

 since their power of resistance is not equal. 



Salts of potash seem much less favorable than the salts of magnesia, 

 and especially than salts of soda. Life ceased first iu the ioduret, the 

 bromide, the chloride, and the sulphate of ])otassium, and in solutiim 

 No. 10, the i)revailing element of which is chloride of i^otassium. 



The salts of soda and magnesia still maintained life when the animals 

 had succumbed in the salts of potash. Solution No. 9, for instance, the 

 principal element of which is chloride of magnesium, preserved its in- 

 habitants alive much longer, and the same applies to the sulphate of 

 magnesia alone and in solution No. 11. 



The resistance of the palourdes in the Vichy water shows the favor- 



