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THE BEEATHING SYSTEM OF FLOWERING PLANTS 

 AND THEIR ALLIES. 



[By the Rfa\ J. E. VizE, M.A., F.R.M.S.] 



In a Club like ours, we take it fur granted that the fact of vegetables having the 

 power to breathe is well known. They could not exist for long if it were not so, 

 through want of fresh air passing into them. Trees, shrubs, jjlants, do In-eatlie. 

 Perfectly true it is that there is not one uniform stereotyped system in which this 

 is done, and that there are modifications in the breathing is certain. Most plants 

 breathe on the upper surface and the under surface of the leaf, but not necessarily 

 all of them. Take the Water Ranunculus, for instance. The upper portion of the 

 leaf only has these breathing organs. Why so ? Because the lower portion touches 

 the water and does not need them. This plan holds good with many of the 

 aquatic species. 



But for the benefit of those who have not studied these things, and perhaps 

 have not known of their existence, let me explain how the work of breathing is 

 done. There is in nearly all the surfaces of leaves a cavity, and from within and 

 without air is conveyed through the leaf, and therefore through the whole 

 tree. The proper term for these cavities is stomata. Let us, however, take 

 the simpler word, breathing-tube, and use it instead of the classical word. 

 They are queerly shaped things, scattered very much on the leaves, the 

 stems, the stalks, and even the bulbs of flowering plants. Grasses have them 

 abundantly. They are easily detected under the microscope. Possibly some 

 may wish to know how they are to be obtained as permanent objects of 

 examination. My plan has been simple enough, and I daresay, may be generally 

 adopted. I, of course, choose my specimen, say, a tulip. Gather your tulip leaf, 

 do not operate upon it at once, but leave it until it become.s somewhat limp, .say 

 an hour or two after having been gathered. Then with a very sharply-pointed 

 knife cut through the outer skin of the tulip just enough to cut through the skin, 

 but not to cut far into the cells of the leaf. Then with the back of your knife 

 raise this skin very tenderly. Take hold of it with your nail or a broad pair of 

 forceps, or something which will give you a firm hold on the cuticle. Pull gently, 

 and you will get, if successful, which is especially likely to be the case when 

 manipulated under water, a beautifully thin skin. Upon this skin are the mouths 

 of the plant. Lay it carefully on a slip of glass and examine under the 

 microscope, — you will then see these apertures for the breathing arrangement. 

 These mouths are very interesting. No uniformity of arrangement exists such as 

 equidistance. No two touch each other. Yet they are connected together, some- 

 times by two vein-like grooves, sometimes by three or four grooves. Moreover, 

 these veins are endless as to variety. They may be toleralily regular or very 

 irregular ; tolerably straight, as in the grasses, or anything but straight. 



These veins, it seems to me, correspond somewhat with the shape of the leaf. 



