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CH. X.] the earth are in alternate rows, so that the influence of the fluid, in whatever way it may gain access, cannot but be different.

Note 3, p. 114. As vision is perceptive, &c.] The argument here is interrupted and obscured by parenthetical explanations; but the purport is, that the senses are the sole judges of sentient impressions through all their degrees of intensity, and that, as sensibility is a mean, they cannot discriminate such as are far above or below the allotted medial standard. There is a seeming discrepance, however, in employing the term invisible as analogous to impossible on other subjects, as vision is not altogether lost in any darkness; but a creature without feet could not continue its existence, nor a fruit without the kernel continue its species.

Note 4, p. 115. The impotable as well as the potable, &c.] The impotable implies, of course, whatever is neither moist nor capable of becoming moist, and every such substance must, necessarily, pain—be very disagreeable to, that is—and pervert the Taste. All these passages, however, while proving that moisture is required for savour, point to a want of knowledge of the salivary and mucous glands which were yet to be discovered. But over and above the due conditions of moisture, there was still required the knowledge of the nervous system to account for the many perversions of Taste which are manifested, both in sick and well; and manifested, at times, without any apparent cause. It will occur to many, besides, how differently the