38 Kraemer : The Crystals in Datura Stramonium 



monoclinic system. Instead of the crystals having a true deltoid 

 form like a tetrahedron, one axis is frequently as much as twice as 

 long as the other two axes. It may be mentioned that it is not 

 unusual to find associated with these hemiedral forms crystals 



p 



which resemble the octahedrons or hexahedrons of the isometric 

 system, but the greater difference in the length of one axis indi- 



m 



em 



In the stem we find the same kind of crystals as well as 

 a similar distribution of them that we noted in the root. The 

 crystals may in some cases be larger, measuring as much as 15// 

 in their longest axis. There are also present in some of the cells 



monoclinic prisms (about 20 x 5 X $ ft) as well as rosette aggre- 

 gates made up of about 12 of these prisms. In some specimens 

 these prisms are replaced by aciciilar crystals (35// long) which 

 may be united or aggregated to form large sphere crystals. 



■ 



In the petiole of the leaf we find numerous hemiedral crypto- 

 crystalline crystals (20 x iox 10/i). There are, however, in ad- 

 dition many monoclinic prisms (14 X iox 10 //) or pyramids 

 (25 x 10 x 10/i) or a few rosette aggregates of crystals (30 ft in 

 diameter). In some specimens the hemiedral forms may be largely 

 replaced by monoclinic prisms (15 x 4 X 4 /1) or pyramids (iox 

 3 x 3/i) or acicular crystals (35 jut in length). In the parenchyma 

 of the nerves of the lamina there are many cells that possess 

 cryptocrystalline crystals, but we also find large monoclinic pyra- 

 mids (28 x 15 X 15 jte) and rosette aggregates (28 fi in diameter). 

 There are also present in some specimens numerous small prisms 

 and acicular crystals. 



In the mesophyll of the leaf the cryptocrystalline crystals are 

 entirely replaced by rosette aggregates (17 to 24 p in diameter) : 

 one occurring in each parenchyma cell directly below the palisade 

 layer. 



In the parenchyma of the flower stalk we find very small 

 rosette aggregates of crystals (10 /z in diameter). In the paren- 

 chyma of the calyx a few small prisms (1-3 fi long) and rosette 

 aggregates (10—14 n in diameter) are found. 



In the parenchyma of the corolla are small prisms (2-3 // long) 

 and some small rosette aggregates. In the filaments of the sta- 

 mens there are some exceedingly small cryptocrystalline crystal- 



