60 



BOTANT. 



Pig. 46.— Crystals of calcinm oxalate. 

 The right-hand portion of the flgare 

 shows two raphis-oells of the Khubarb, 

 with their contained raphides, and one 

 crystal enlaraied. On the left is acrys- 

 tal from the beet. 



alents of water of crystallization ([Ca 0], 0, 0,+ 6 H,0). 



They may be simple (Fig. 47) or combined into compound 



I crystals (Fig. 46) ; many of 

 the former are sometimes 

 found imbedded in the sub- 

 stance of the cell-wall of the 

 fibre-cells of certain Gymno- 

 sperms (Fig. 

 47). Simple 

 crystals oo-J 

 cur also with-1 

 in the cell- 

 cavities of 

 many plants. 

 The c m - 



Much magnifled. ' pound f OrmS 



are very Yarioiis ; they almost always 

 occur in cell-cavities, as in the beet (Fig. 

 46) ; and it not infrequently happens that 

 both simple and compound crystals are 

 found in the same plant, even in contigu- 

 ous cells, as is the case in the onion bulb, 



80. — Crystals of calcium carbonate 

 (Ca CO3) occur less frequently than those 

 just described. Their most striking form 

 is that seen in the structures named cys- 

 toliths (Fig. 48). These possess a curious 

 structure ; a club-shaped or stalked out- 

 growth of cellulose projects into the in- 

 terior of a cell, and upon and in this mul- 

 titudes of small crystals are grouped. 

 Other forms of calcium carbonate crys- 

 tals are to be found in plants — e.g., in the 

 Myxomycetes. 



According to some observers, crystals "^{fj^S^ T^llL^a 

 of calcium phosphate, calcium sulphate, ™»-aA«ts.-Arter sachs. 

 and silica are occasionally to be met with in plants.* 



* See an article on plant-crystals by t)r. Lancaster In the Qr. Jr. of 

 Mic. Science, 1863, p. 343 ; also articles by Professor Gulliver in the 

 eame journal fnr 18''4, IRRR. nnd 18fi9. 



