CALCIUM OXALATE 



531 



regularly, for example, in the LlLIACEAE, ORCHIDACEAE, COMMELYNACEAE, 

 (Fig. 214 a), Musaceae, etc. Among Dicotyledons, also, they are found 

 in a variety of genera, such as Galium, Impatiens, Vitis, Phytolacca, 

 etc. 



(d) Spherical aggregates, sphaerraphides or drusy masses (Dru sen). 

 Sphaerraphides are rounded crystalline aggregates, the shape of which 

 has been compared to the spiked mace-heads of medieval warfare ; such 



Fig. 214. 



Crystal-sacs. A. Tubular raphide-sac from the stem-cortex of Tradeseantia zebrina. 



B. Crystal-cells from the secondary phloem of Aescidus Hippocasta,>um'An the 

 lamellar parenchyma (if the petiole of Trapa nutans. D. Cell from the pulp ofa 

 Rose-hip containing a twinned crystal suspended by cellulose trabeculae. 



aggregates almost always occur singly in the crystal-cells. This form 

 of calcium oxalate is of very frequent occurrence indeed : a few of the 

 many families in which it has been observed are the Chenopodiaceae, 

 Caryopiiyllaceae, Cactaceae, Araliaceae, Malvaceae and Tiliaceae. 



(e) Genuine sphaerocrystals or sphaerites. Sphaerites of calcium 

 oxalate are somewhat rare in the vegetable kingdom ; they are found 

 in the pith of the twigs of Terminalia Bellerica and T. paniculata 

 (according to Von Hohnel), in various Cactaceae (according to Mobius), 

 and in the testa of Misanthe noctiflora, Silcnc Gucubalus, and certain 

 other Caryopiiyllaceae (according to Hegelmaier). 



In many plants, calcium -oxalate crystals occur in more than one 

 of the above-mentioned forms. According to Sanio, for instance, 



