60 



BOTANY. 



alents of water of crystallization ([Ca 0], C 4 O.-f 6 H,0). 



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

 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- 

 sperins (Fig. 

 47). Simple 

 crystals oc-, 

 cur also with- 1 

 in the cell- 

 rig. 46. -Crystals of calcium oxalate. Cavities of 



The right-hand portion of the figure rr , 01 T,T-,-,l Q rifo 



shows two raphia-cell* of the Khubarb, many plants. 



with their contained raphides, and one r Pl 1p P n rn 



crystal enlarged. On the left is a crys- J 



tal from the beet. Much magnified. pound f Orm.8 



are very various ; 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 C0 3 ) 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. Fig 47 ._ C rystais of 



According to some observers, crystals SSSi 2?" rJ&SJSa 

 of calcium phosphate, calcium sulphate, miraHUf. -\ttar Sachs. 

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



* See an article on plant-crystals by Dr. Lancaster in the Qr. Jr. of 

 Mic. Science, 1863, p. 243 ; also articles by Professor Gulliver in the 

 game journal for 18^4, 18flft and 18^9. 



