ON MICROSCOPIC DISCOVERY. 



605 



The pores of the skin are minute excretory 

 ducts, discharging the superfluous humours 

 of the body ; they also convey to the absorbent 

 vessels of the true skin, the fluid and gaseous 

 products of the surrounding atmosphere. 

 Hence it is, that a derangement of these mi- 

 nute valves, or a suspension of their functions, 

 causes serious injury in the animal economy ; 

 and it is almost a demonstrable fact, that all 

 the diseases to which the human body is lia- 

 ble, take their origin from a partial or gene- 

 ral interruption to the porous machinery of the 

 skin. It will readily be conceived that great 

 disorders must arise in the system when the 

 exhalation of humours is stopped, and those 

 active agents the absorbents, are inactive. As 

 a preservative of health, nothing is more wor- 

 thy of attention than this simple precept ; 

 wash the skin clean, remove with flesh-brushes 

 all the scales which are daily shed, and which 

 if suffered to remain upon the skin, mat toge- 

 ther and impede the action of the pores ; when 

 the perspiration is too scanty, as evidenced 

 by extreme dryriess of the skin, use medicines 

 that will determine the humours to the sur- 

 face ; when the perspiration is too profuse, as 

 indicated by an excess on the least exertion, 

 take medicines to moderate the activity of the 

 secretory organs. Here is a volume of do- 

 mestic medicine in a few lines. 



To view the pores, it is necessary with a 

 keen-edged penknife, to shave off the outer 

 surface of the skin as thinly as possible, and 

 then to cut a second piece from the same place ; 

 there is no fear of inconvenience from the ope- 

 ration, if it be performed with a light hand, 

 and the skin be taken from between the fin- 

 gers. The pores are covered by the scales ; 

 indeed it would appear that the latter are prin- 

 cipally, if not wholly designed, as a protecting 

 covering to these minute vessels. The num- 

 ber of the pores dispersed over the human 

 skin is too large for our conceptions ; and when 

 we state, that on thelowestestimate,it amounts, 

 in round numbers, to two thousand millions ; 

 we offer this announcement, simply as an ef- 

 fective comment on the scriptural declaration, 

 that "we are fearfully and wonderfully made." 

 The process of perspiration may be pleasing- 

 ly observed on a warm day, in the following 

 manner : wash the hands with soap and warm 

 water, and dry them thoroughly, then with a 

 magnifier of one half inch focal distance, ob- 

 serve the small ridges in the palm of the hand, 

 and along the edges of these, the perspiration 

 will be seen arranged like rows of pearls, or 

 more properly, like dew drops on a flower. 



The scales of fishes are objects of great in- 

 terest to the microscopic inquirer, from the 

 variety of form and texture observable in them. 

 Exceedingly minute scales have been detected 

 by the microscope lying between the epider- 



mis and the true skin of an eel. We extract 

 a few general remarks on this class of objects 

 from Baker. " These scales are not supposed 

 to be shed every year, nor during the whole 

 life of the fish, but have an annual addition 

 of a new scale, growing over and extending 

 every way beyond the edges of the former, in 

 proportion to the growth of the fish ; some- 

 what in the same manner as the wood of trees 

 enlarges yearly, by the addition of a new cir- 

 cle next the bark ; and as the age of a tree 

 may be known by the number of ringlets its 

 trunk is made up of, so in fishes, the number 

 of plates composing their scales denote to us 

 their age. Mr Leeuwenhoeck took some 

 scales from an extraordinary large carp, forty- 

 two inches and a half long, and thirty-three and 

 a quarter in the round, which were as broad as 

 a dollar. These he macerated in warm water, 

 to make them cut the easier ; and then cutting- 

 oblique ly through one of them, beginning with 

 the first formed, and very little scale in the 

 centre, he by his microscope, plainly distin- 

 guished forty lamellae or scales, glued as it 

 were over one another ; whence he concluded 

 that the fish was forty years of age." To the 

 arguments here used we have sundry objec- 

 tions to offer : in the first place, the scale of a 

 fish increases exactly in the same manner as 

 a crystal, (say the crystal of common salt), by 

 superposition of thin laminae, and so far as 

 we have observed, it is as impracticable to as- 

 certain the exact number of layers in the one 

 as in the other; and consequently we can de- 

 rive from the scales no perfect data whence 

 to compute the age of the fish. And in the 

 second place, the yearly addition of a layer to 

 the scale, is nothing more than a mere suppo- 

 sition, from an overstrained analogy. If then, 

 the superpositions be effected in other than 

 yearly intervals, the age cannot be determin- 

 ed ; neither, we presume, can it be determined 

 by admitting the yearly additions, for we are 

 not assured when using the deepest magnifiers, 

 that we see the ultimate divisions. Indeed 

 Leeuwenhoeck himself states, that the scales 

 of fishes are composed of an infinitude of layers 

 or laminae ; an admission founded in fact, and 

 altogether fatal to the fanciful hypothesis we 

 have noticed. These objects require to be 

 viewed both by transmitted and reflected light, 

 in order that all their peculiarities of surface 

 and structure may be satisfactorily observed. 

 The crystalline lenses of fishes and other ani- 

 mals exhibit a most astonishing structure un- 

 der the microscope. We are indebted to Sir 

 David Brewster for a minute and particular 

 description of these formations, which we shall 

 present to the reader in his own words, intro- 

 ducing it by two or three sentences from Mr 

 Pritchard's Microscopic Objects. '* If the crys- 

 talline lens in the eye of a fish, be minutely 





