22 



and lemon, and of the i^oplar and allied trees ; in the ovary of 

 Oompositae, &c. 



The significance of these crystals, which had been discussed at 

 former meetings of the Society, does not seem to have been 

 recognised in our books of botany and philosophical agricul- 

 ture. Some of the di-aivings now jiresented are quite new, 

 and altogether they suggest interesting and important 

 views in physiological botany. The crystals are composed 

 in great part of salts of lime, and must, when restored to the 

 soil in the decayed leaves and other parts, serve as valuable 

 maniu-e, and when eaten in the fresh or dried plants by animals 

 form an essential constituent of their frame. The quantity of 

 the crj'stals is immense in the Legumens, which are so valuable 

 as fodder ; in the seeds or fruits so much fed on by birds ; and 

 even in the duckweeds, which form much of the food of the 

 young aquatic birds and of many groups of invertebrates. And 

 no doubt, when this minutely divided crystalline matter in the 

 plants is taken by animals as aliment, it is in the most favour- 

 able state for assimilation with the bones or other tissues ; so too 

 when restored to the earth in vegetable humus it forms a very 

 valuable manure, always highly esteemed in the state of leaf- 

 m.ould by the gardener. The same reasoning will apply to 

 medicine. Thvis, for example, Sarsaparilla has long been 

 known for its efficacy, especially in such kinds of cachexy as are 

 connected with diseased bones ; and the best samples of this 

 plant afford abundance of raphides, which, according to the 

 analyses of Dr. Davj', consist mainly of phosphate of lime. A 

 considerable quantity of starch also occurs in Sarsaparilla ; and 

 so no wonder that some of our most eminent surgeons, like the 

 late Sir Benjamin Brodie, found it most useful in large doses. 

 But the reason why never so plainly appeared as since the 

 researches on these crystals, nor indeed of several of their impor- 

 tant functions in the economy of nature. It is remarkable, too, 

 how valuable characters in systematic botany are proved to be 

 afforded by raphides, as described at former meetings of the 

 Society. And the true Sarsaparilla may be thus easily distin- 

 guished from the false. This latter, often called American 

 Sarsaparilla, contains numerous sphaeraphides — as do the allies 

 of its order, Araliaceae — but no raphides at all. 



No adequate descriptions and figures have yet been published of 

 the physiological significance and marvellous distribution and forms 

 of plant- crystals. They are often surprisingly beautiful, and may 

 well afford inexhaustible subjects at all seasons for the employment 

 of the microscope. Were we to describe a tree as invested through- 

 out by a most delicate network of microscopic crystals the descrip- 

 tion might seem to be rather wild imagination than sober reality. It 

 is nevertheless the strict truth, as these researches have plainly 



