322 On the Naturalization of FM] 



ment. I stated befofe, th&t it admitted the 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 as 40 to 150. In another, peculiarly dry, 

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

 lowest, it cannot ever 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 ; or, 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 



within 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 alj 

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

 fruitless. It was stated before — the question is simply twofold 5 



