WITH THE MICROSCOPE. 165 



character of the crystals alone. In the bulb of the common onion, 

 in the leaves of the hyacinth, and many allied plants^ crystals may 

 be detected. Raphides are met with in only three orders of British 

 dicotyledons : Balsaminaceae, Onagracise, and Rubiacise (Gulliver), 

 but they are commonly found in many monocotyledons. In trans- 

 verse sections of the thick leaves of the India-rubber plant collec- 

 tions of small crystals are seen in certain cells. See Mr. Gulliver's 

 papers in the Microscopical Journal, especially the number for 

 January, 1866. 



239. Of the Circulation in the Cells of certain Plants. The cir- 

 culation or cyclosis of the contents of the vallisneria, anacliaris, 

 ikara, and nitella, rmy be observed without any difficulty. In all 

 these the movement is due to the vital properties or powers of the 

 germinal matter which moves round and round the cell ; the hard 

 cell wall preventing its escape, and rendering movements in a right 

 line impossible. If subjected to examination under the highest 

 powers, however, certain precautions are necessary. The thinnest 

 possible layer should be removed with a thin but very sharp knife, 

 from the surface of a young leaf of vaHisneria or anacharis and the 

 t\vo thin pieces thus- obtained must be carefully placed on the slide 

 with a drop of water and covered with the thinnest possible glass, 

 care being taken to* prevent it from pressing firmly upon the freshly 

 cut surface. 



It not unfrequently happens that cyclosis has entirely stopped in 

 the cells submitted to examination, but after the fragments of the 

 leaf have remained still for a short time the movement recommences, 

 especially if slight warmth be applied ; and it is a good plan, espe- 

 cially in winter, to place the sections which have been made in water, 

 in a small corked glass tube, which may be carried in the pocket for 

 a quarter of an hour or more before they are to be subjected to 

 examination. 



Facts of the utmost general interest and importance may be 

 demonstrated in vallisneria by the aid of the highest powers. The 

 stream which moves round and round the cell, and looks like pure 

 water under a twelfth, is found to be composed of extremely minute 

 and apparently spherical particles, endowed with active motor power, 

 if examined by a ^ or -^, pi. XXXVIII, fig. 244. The green chlo- 

 rophyll masses are urged on by the actively moving germinal matter. 

 One portion of the active, colourless, moving matter is seen to out- 

 strip another portion, amongst which it gradually blends and incor- 

 porates itself, to be, in its turn, outstripped by other portions. 



'Solid particles are often suspended in moving germinal matter, 

 and appear to move of themselves, although, really, they are per- 



