WITH THE MICROSCOPE. 1 67 



of the spine a number are seen to be adherent. Often in specimens 

 of this plant the deposition has been so rapid that there was not 

 sufficient time for the complete condensation of the component cor- 

 puscles. In these instances a number of them have been caught and 

 loosely enclosed in one or more cavities, as shown at d, d. The walls 

 of these containing cavities do not possess a definite outline because 

 they are lined with corpuscles in all their different stages of transition. 



The course which the current takes in the cells of vallisneria, 

 anacharis, &c., is indicated by the arrows in fig. 247, after Dr. Branson. 



Vallisneria, chara, nitella, and anacharis may be kept without 

 difficulty in glass jars in s our rooms, and tradescantia will grow in 

 pots outside the window, and flower freely even in London. Pale 

 or white-flowered plants should be selected for observation. 



The circulation in the cells of vallisneria. and the movements of 

 the cilia of small animalcules or ciliated cells under a high power with 

 the new binocular of Messrs. Powell and Lealand, p. n, once seen 

 can never be forgotten, for the mind seems to have realised the 

 actual state of things occurring during the life of the plant, in a 

 manner which before was not possible. 



2GO. Of Preserving Vegetable Tissues permanently. Vegetable 

 tissues may be preserved according to the plans already given for 

 animal tissues. Syrup and glycerine are excellent preservative 

 media. The germinal matter of vegetable tissues may be stained 

 with carmine, the course of vessels and tubes may be demonstrated 

 if filled with coloured fluids which they will imbibe by capillary 

 attraction, especially if evaporation be promoted from the leaves. 



Seaweeds which are to be preserved permanently, should be 

 allowed to soak for some time in pure water. Small pieces may 

 then be removed and transferred to glycerine. Some of the most 

 beautiful vegetable preparations which I have seen have been 

 mounted in glycerine. The mixture of gelatine and glycerine, and 

 gum and glycerine will also be found good media for mounting 

 many vegetable structures, and chloride of calcium forms a useful 

 preservative fluid in many instances. Creosote fluid, carbolic acid 

 water, very dilute spirit and water, and even simple distilled water 

 will preserve some vegetable tissues for a great length of time. The 

 pith of the stem of various plants, the epidermis, and many other 

 vegetable tissues may be preserved as dry objects very satisfactorily. 



26L Of Collecting and Mounting Diatoms.- In collecting dia- 

 toms and other organisms from pools, the pocket microscope 

 described in p. 14, will be found very useful. A little of the sedi- 

 ment suspected to contain them may be placed in the animalcule 

 cage and examined by the side of the pool. The waistcoat pocket 



