CRYSTALLIZATIONS. 



Ill 



Fig. 171. 



b<irk were moistened, and examined by the microscope, the arrangement of crys- 

 tals appeared like an elegant piece of mosaic work, as shown in figure 171, which 

 is a section of the bark of a species of poplar, the crystals in 

 the cells of the bark being either single or compound. The bark 

 of the locust, willow, chestnut and various other trees exhibits a 

 similar appearance. In the densest woods, such as mahogany and 

 lignum vita3, the crystals may be found by scraping the wood into 

 a watch-glass filled with water, picking out the woody particles 

 and then examining the residue; and if by this process the crystals 

 are in any case sparingly discovered, they will be revealed in great 

 quantities if the ashes of the wood to be examined are imbedded 

 in balsam in the manner before described. 



The crystals are likewise detected in the minute particles that 

 fall from worm-eaten wood, or sawdust, and in the finer par- 

 ticles of ground dye-woods, such as fustic Brazil wood, camwood, 

 logwood, sandal wood, &c. 



Prof. B. next proceeded to examine the leaves of trees, which 

 were likewise found to abound in crystals. By slowly and care- 

 fully burning the leaf until the ashes became white, and covering the residuum 

 with Canada balsam, the incombustible portions of the leaf exhibited a skeleton 

 of its figure. When a full grown leaf was thus prepared and placed under the 

 microscope, the course of the minutest veins in the leaf was seen traced out in 

 the ashes by a row of transparent crystals. In young leaves these crystals were 

 observed only to exist in the main stem, and along some of the principal branches. 

 In the leaves of other plants the arrangement of the crystals was found to be 

 different, being scattered throughout the cellular tissue in star-like groups. The 

 crystals of the primitive form, represented in figures 172, 173, 174, 175, 176 and 

 177, were found by Prof. B. to exist Fig.ns. Fig.rra. Fig.m. Fig.no. 

 abundantly in more than one hundred 

 species of plants, belonging to more than 

 thirty different families, which comprise 

 the great majority of dicotyledonous trees 

 and shrubs, besides many herbaceous 

 plants. The primitive form displayed 

 in figures 165, 166, 167, 168, 169, 

 170 and 171, was found to be far 

 more sparsely scattered in dicotyledo- 

 nous plants, than the forms found in the 

 last set of figures ; while a third form 

 which is exhibited in figures 178 and 

 179, is more abundantly discovered than 

 the second form in the same division 

 of plants, and is believed by Prof. B. 

 to be composed of crystals of the two 

 first forms. 



176. 



177, 



