382 On the Naturalization of Fish. 



ment. I stated before, that it admitt^t he ^sea, by leakage, in 

 summer, when there was little comparative supply of fresh 

 water, and was therefore brackish, or saline. I have since 

 ascertained the exact proportion of salt in the water, at those 

 times when the fresh water is least. In the driest and hottest 

 part of one summer, the proportion of salt in it, as compared to 

 the sea without, was a/40 to 150. In another, peculiarly dry, 

 1827, it was one half; and the water, having then been at the 

 lowest, it cannot even be computed to exceed this. Moreover, 

 this period of saltness cannot easily, even in such a summer, 

 occupy more than the months of June, July, August, and Sep- 

 tember; of, more strictly speaking, it is probable, scarcely one 

 half of that time in general, in so rainy a climate ; a climate 

 equalling Penzance in the quantity of rain. 



In winter, that is, during five or six months, or less, if any 

 objector pleases, it is fresh. That cattle drink it freely, is not 

 an exact chemical proof; but I must admit, that I have not 

 analyzed the water at that period, holding the objection in great 

 contempt. It may be sufficient to say, that it then occupies a 

 space of about sixteen acres, or increases to this magnitude 

 from four and a half acres ; so that it cannot, at least, be very 

 salt, while the fish, and the mullet in particular, are found in 

 the remotest ditches, among the meadows. But, in defect of 

 an analysis, which I have not had the means of making,, there 

 is a valid reason why the water should be fresh when the size 

 of the pond is much extended. The presence of sea-water in 

 it, is, in all cases, the consequence of a depression of the water 

 within the sea-wall, which allows of leakage or infiltration at 

 the upper part, so as, in high tides, to equalize, as far can be 

 done in the short period of high water, the levels within and 

 without. This, it is plain, must cease whenever the water 

 "M^irkhin is higher than the sea without ; and hence it is that there 

 can be no access for the salt water in the winter or rainy 

 months. 



Enough of the mere fact : the objections derived from which 

 ought not to demand an answer among physiologists ; while to 

 those who argue physiological points in utter ignorance of all 

 that belongs to physiology, it is probable that all answer is 

 fruitless. It was stated before ; the question is simply twofold ; 



