324 MICROSCOPIC FOKMS OF VEGETABLE LIFE. 



in the healthy state, is lined by a layer of green oval granules, 

 which cover every part, except two longitudinal lines that remain 

 nearly colorless (Fig. Ill, b); and a constant stream of semi-fluid 

 matter, containing numerous jelly-like globules, is seen to flow 

 over this green layer, the current passing up one side, changing 

 its direction at the extremity, and flowing down the other side, 

 the ascending and descending spaces being bounded by the 

 transparent lines just mentioned. That the currents are in 

 some way directed by the layer of granules, appears from the 

 fact noticed by Mr. Varley,' that if accident damages or removes 

 them near the boundary between the ascending and descending 

 currents, a portion of the fluid of the two currents will inter- 

 mingle by passing the boundary ; whilst, if the injury be repaired 

 by the development of new granules on the part from which 

 they had been detached, the circulation resumes its regularity, 

 no part of either current passing the boundary. In the young 

 cells, however, the rotation may be seen, before their granular 

 lining is formed. The rate of the movement is affected by any- 

 thing which influences the vital activity of the plant ; thus, it is 

 accelerated by moderate warmth, whilst it is retarded by cold; 

 and it may be at once checked by a slight electric discharge 

 through the plant. The moving globules, which consist of 

 starchy matter, are of various sizes ; being sometimes very small, 

 and of definite figure, whilst in other instances they are seen as 

 large irregular masses, which appear to be formed by the aggre- 

 gation of the smaller particles.'' The production of new cells, 

 for the extension of the stem or branches, or the origination of 

 new whorls, is not here accomplished by the subdivision of the 

 parent cell, but takes place by the method of out-growth (Fig. 

 Ill, B, e, /, g, h), which, as already shown (§ 198), is nothing but 

 a modification of the usual process of cell-multiplication ; in this 

 manner, the extension of the individual plant is effected with 

 considerable rapidity. When these plants are well supplied 

 with nutriment, and are actively vegetating under the influence 

 of light, warmth, &c., they not unfrequently develope "bulbels," 

 or gonidia of a peculiar kind, which serve the same purpose' in 

 multiplying the individual, as is answered by the zoospores of 



' " Transactions of the Microscopical Society" (First Series), vol. ii, p. 99. 



2 This interesting phenomenon may be readily observed, by taking a small portion 

 of the plant ont of the water in which it is growing, and either placing it in a large 

 aquatic box (J 68) or in the zoophyte-trough (§ 69), or laying it on the glass stage-plate 

 (§ 67) and covering it with thin glass. The modification of the stage-plate which is 

 termed the " growing-slide," will enable the Mioroscopist to keep a portion of Chara 

 under observation for many days together; and this is a mncli simpler and more con- 

 venient arrangement than the method devised by Mr. Varley for growing Chara in 

 bottles ; since the bottle requires a special " phial-holder" for fixing it on the Microscope 

 stage, and the convexity of its surface produces some distortion of the image. The lat- 

 ter method, however, has its advantages for those who wish to make a special study or 

 a frequent exhibition of the phenotnenon in question; and such should consult Mr. 

 Varley's memoir in the " Transactions of the Society of Arts," vols, xlviii, xlix, 1; some 

 parts of which are cited by Mr. Quekett in his " Practical Treatise on the Microscope, 

 Third Ed. pp. 1G6, 397, et seq. 



