LEMNACEJE. 19 



miucral substances, as silica and carbonate of lime, also sulpbato of lime, are found in 

 a crystalline form in the tissues of plants ; but tlicy do not constitute what are called 

 raphides. 



In a paper on " Eaphides as Natural Characters in the British Flora," in the 

 volume of the " Quarterly Journal of Microscopical Science " for 18GG, Professor 

 Gulliver gives the following summary of the occurrence of raphides in British 

 plants : — 



" Only three orders of British Dicotyledons can be as yet characterised as raphis- 

 bearers, and these are Balsamineaj, Onagraces, and Rubiaceis." " In Monocotyledons 

 raphides are much more plentiful than in Dicotyledons, so no wonder that a partial 

 examination should have led to the behef that ' they are abundant in Monocotyledons 

 generally.' This and other such vague and incorrect statements are current in our 

 best and latest treatises of Phytotomy ; whereas the truth is, that, however raphides 

 may abound in many Monocotyledons, they are either very scarce or absolutely wanting 

 in several extensive orders of this class. As before mentioned, our indigenous plants 

 are only now under consideration, and we shall soon see that about a fifth part of the 

 ' Manual of British Botany ' is occupied by Monocotyledons and Cryptogameas 

 Ductulos©, which I have searched in vain for raphides. 



" Bidyogerwe, — In all our plants of this group raphides are plentiful, and they occur 

 in every one of the exotic members of it that I have examined ; only in Moxlmnjlda 

 raphides are mostly replaced by crystal prisms. I have found that the beautiful 

 shrub Lapageria is also a raphis-bearing plant. In the lineal series of the natural 

 arrangement, the Dictyogenffi stand isolated by this character between Coniferis and 

 Hydrocharidacese, two orders in which it is wanting. 



^^ SydrocltaridaccoE. — This order is remarkable as being devoid of the raphidian 

 character, though standing between two groups, Dictyogense and Orchidacea;, in full 

 possession thereof. 



" OrcMdacece. — Raphides were found in every plant, British and foreign, that I have 

 examined of this order. They are by no means confined to the sepals, as might be 

 supposed from current descriptions, but are common in the placenta and ovary, in 

 the stem and the leaves, and parts which are modifications of leaves, and in the roots. 

 The raphides are commonly much shorter than their soft pale cells, and may be well 

 seen without disturbing them through the semitransparent edge of the leaf of Neottia 

 spiralis. 



" Tndacece. — True raphides are scanty and often not to be detected in this order, 

 but it abounds in crystal prisms. These last occur in all our plants except Sisij- 

 rinchiiun aiiceps, in which, as well as in the exotic S. Bormiulianwn, and jS'. striatum, 

 I have failed to find any such crystals. They are very remarkable in the common 

 garden species of Iris. 



" Amaryllidaceai. — In all our Amaryllids raphides occur. They may be well seen in 

 the leaves, scape, ovary, bulb- scales, and bulb, and smaller and less plentiful in the 

 bulb and perianth. 



" Asparagaceae. — All our plants of this order are raphis-bearors. This character is 

 common in the root, leaves, perianth, and ovary of asparagus, &c., and more remark- 

 able in the perianth than in the leaves of Ewsc^ts. 



" Liliacece. — Of the four tribes of this order as they stand in the 'Manual of British 

 Botany ' — 



" 1. Tidipece. Destitute of raphides. 



" 2. Asplwdelem with Gagea and Allium. Also devoid of raphides, though tliey 



abound iu Oruilhogalum and Scilla. 



D 2 



