Thomas. — Metallic Salts 123 



An interesting point was found when a land-locked 

 pond was discovered to contain a large number of this 

 same species, Fundulus heteroclitus. The pond was lo- 

 cated on one of the islands near Woods Hole, and so situ- 

 ated that it was possible for a very high tide to wash into 

 it during a storm. Information that this happened every 

 two or three years, was obtained from Mr. Vinal Ed- 

 wards. It is highly probable that the Funduli were car- 

 , ried into the pond in this manner, and gradually accus- 

 tomed to the fresh water. The water from this pond was 

 fresh enough to be nearly drinkable and showed a den- 

 sity of only 1.0008. The Funduli taken from this source 

 lived well in fresh water (hydrant water). 



Although of the same species, these fish were more 

 j delicate than those taken from salt water, which might be 

 expected ; as they had less of the elements to resist than 

 if they had been in the open waters, where they would 

 be tossed about by the waves, and exposed to the rougher 

 conditions there found. The scales of these fish were 

 thinner and of a softer texture than those of the fish 

 taken from salt water, and the fish were somewhat smal- 

 ler than the average size of those used in the before des- 

 cribed experiments, which only seemed to indicate that 

 they were younger. 



As might be expected the salts were much more toxic 

 to these fish in fresh water than to the same species in 

 salt water. This tends to the confimation of the belief 

 that the salts in sea water were antagonistic in the ex- 

 periments in which it was the basic media used. 



Lead nitrate proved to be fatal within twelve hours at 

 a concentration of three parts per million ; aluminium sul- 

 phate, which is often used in the process of removing 

 suspended matter from drinking water, was fatal within 

 thirty-six hours at a concentration of fourteen parts per 

 million, and in five days at a concentration of seven parts. 

 It was impossible to use these salts in sea water on ac- 

 count of the insoluble precipitates which were at once 

 formed. Zinc sulphate was fatal within forty-eight hours 

 at a concentration of ten parts per million, but was non- 



