82 On the Regular Arrangement of Crystals in Plants. 



bellino repleta ; vesiculis nudo oculo distinctis. Chudleigh, Oc- 

 tober 1845. 



Globose, at length depressed, half an inch in diameter ; at first 

 white, but soon, especially when rubbed, assuming a reddish tinge, 

 pouring out when cut a rich pale red cream-like fluid. Spo- 

 rangia as large as those of Endogone pisiformis. A very distinct 

 and interesting species. 



X. — On the Regular Arrangement of Crystals in certain Organs 

 of Plants. By Edwin J. Quekett, F.L.S. 



It rarely happens in plants that any definite organ is the seat of 

 crystalline collections symmetrically arranged, though the occur- 

 rence of crystals (raphides) in the cells of various portions of a 

 vegetable is extremely common. 



About two years since I met with two organs which exhibit the 

 singular fact, that in them at least the crystals are constant and 

 have a regular arrangement. 



One of these is the testa of the seed of Ulmus campestris f in 

 which the sinuous boundaries of the compressed cells of which it 

 is composed are completely traced out by minute rectangular 

 crystals adhering to their walls. The other is much more re- 

 markable, because, as far as I have been enabled to carry my ob- 

 servations, every member of two allied natural orders have very 

 much the same disposition of these bodies in the same organ. 



If a sepal of any of the ordinary cultivated Pelargoniums be 

 taken, and a portion of the upper cuticle be removed and sub- 

 mitted to the microscope, or if the entire sepal of Geranium 

 Robertianum or lucidum be similarly used, it will be readily seen, 

 by magnifying 300 times, that every cell beneath the cuticular 

 layer is small and round, and in each is a cluster of crystals (con- 

 glomerate raphides), each crystal in the group radiating from a 

 common centre. 



These crystals fill the whole of the cells in the middle of the 

 sepal, and do so likewise all the cells until within a short distance 

 of the margin, where they are absent and the border is transparent; 

 the appearance they present is very beautiful and their numbers 

 and regularity most extraordinary. Their size is about the ^ oV o tn 

 to yj^th of an inch, and their composition appears to be oxalate 

 of lime ; they are insoluble in boiling water, but are soluble with- 

 out effervescence in nitric acid, but after being heated red-hot 

 are soluble with effervescence. 



I have found them in all the species of British Geranium and 

 Er odium, and in all the species of Pelargonium and Monsonia 

 (for which plant I am indebted to Mr. J. Smith of Kew) that 1 

 have been enabled to obtain ; and it is not improbable that they 



