350 



THE AMERICAN 



without water; I could not find any needles or 

 a trace of a crystal. In the heap of starch I 

 remarked a transparent rippled object which I 

 thought was the source of the crystals. 1 then 

 poured a drop of water between the object 

 glasses, but the same object was not changed ; 

 in moving the object I found near by the well 

 constituted needles, where there was nothing 

 of that kind betore. 



I repeated several limes the same experiment, 

 and saw finally the needles take their origin of 

 the surrounding shapeless matter in a twinkling. 

 What are they composed of? Oxalate of lime? 

 This latter salt is obtained by nitric acid, but 

 the needles I saw apiiear more numerous by 

 the addition of nitric acid. Ammonia dissolved 

 them. I took these needles for salseparine. 

 This base is not soluble in water, and crystalizcs 

 in needle-form. So when you force water be- 

 tween the glass plates where salseparine is con- 

 tained, this base is precipitated in the form of 

 needle crystals, following the law of chemistry 

 that every body contained in excess in a men- 

 strum is precipitated in the form of crystals or 

 of amorphous granules. 



In the incrustations of the liber cells of Cin- 

 chona (Pig. 216) we encounter also salts, bnt 

 these are in an amorphous state. Without doubt 

 quinine is to be found there. By the addition 

 of a drop of sulphuric acid the quinine combines 

 with it and forms sulphate of quinine, which 

 being less soluble in water precipitates in very 

 fine needles. At the same time we see that 

 between the layers at the inside of the cellulose 

 membrane (Fig. 210) there appears a series of 



[Fig. 216. J 



holes which grow larger and more iinnicrous, 

 leaving, of the entire cell and its layer, only a 

 mere shadow. 



4. Chlorophyl grains are little rouniti I bodies 

 of a greenish color. They are dis.seminated in 

 most fresh vegetable cells, and abound particu- 

 larly in those which are nearer the outer sur- 

 face of the plant. By oxydation the green color 

 turns yellow and red. The chlorophyl is the 

 matter which gives to foliage its beautiful hues: 



in spring, green in all its variations ; in the fall, 

 yellow, and all transition stages to scarlet. 



5. Granular substances are found in many 

 cells. Sometimes these granules are composed 

 of starchy matters, as detected by their coloring 

 blue with iodine: at other times it is very diffi- 

 cult to study their composition. I remsirked in 

 some cases an active movement of these gran- 

 ules, by their changing their places in respect 

 to one another and to larger bodies in the inte- 

 rior of the cells. 



6. Gases. Under the covering plate in our 

 microscopical researches gases present them- 

 selves, all alike, as bubbles of sharp contour. 

 Chemistry only can tell us what gas is the gen- 

 erator of the bubble in {juestion. In the plants, 

 as it is known, we meet with carbonic acid, 

 oxygen, and atmospheric air. 



For a carbonic acid bubble, we have a test in 

 a solution of chloro-barium (Ba. CI.) in which 

 carbonic acid makes a precipitate of carbonate 

 of barium, which has the form of fine granules. 

 Oxygen, we know, is the gas " par excellence" 

 which is present in vegetable tissues. 



In dry vegetables I found gas ; in living plants 

 I did not detect any free gas-bubbles. It is 

 probable that the oxygen and carbonic acid, the 

 two grand factors in the life of the plants, are 

 merely in solution in the sap, like the carbonic 

 acid in the blood of the lung blood-vessels, and 

 not in the form of free gas. 



7. The last and most important part of the 

 cell contents is the nucleus or cytoblast. 



Schleiden says: "In all tender hairs, almost 

 in every growing portion of cellular tissue in 

 the entire leaves of mosses, especially in Sphag- 

 num, we find in every cell, fastened to the inner 

 wall, a small, mostly plano-convex or lenticular, 

 sharply defined body, strikingly difierent from 

 all other contents of the cell. This is the cyto- 

 blast." 



When perfectly formed it is a flat lenticular, 

 sharply defined, pale yellow body, in which it 

 is easy to distinguish one or two, seldom three, 

 sharply defined, and evidently hollow, corpus- 

 cles, which are called " nucleoli." 



I was not able to discover the cytoblast in 

 leaves of a moss {ITypninn molluscum) . I ob- 

 served at one end a sharper yellowish hue, 

 which in the first moment I took for a cytoblast, 

 but an ampler enlargement showed that it was 

 only the interference of the light in the rounded 

 corner of the cell. In another moss {Sphag- 

 num Jimbriatum) it is otherwise. The cells of 

 the top, which are evidently of more recent 

 building, are without any trace of a cytoblast, 

 whereas in those of ancient date nearer the root, 



