228 Prof. G. Gulliver on the Raphides of Phanerogamia. 



amoug the plant-cells, are so nearly uniform in magnitude and 

 regularl)'^ and beautifully dotted, in subcuticular cells, as to 

 form what might well be called sph?eraphid-tissue. Of this, 

 excellent examples occur in Lythracese, Geraniacese, and many 

 other orders. Sphseraphid-tissue may generally be best seen in 

 the calyx, while the larger and more irregular-shaped sphsera- 

 phides occur abundantly in the leaves. Of the last, Potentilla 

 reptans and its allies afford good specimens ; the first, or sph^e- 

 raphid-tissue, is shown in PI. IV. fig. 13, drawn to a scale of 

 ^-j^-Q-th of an inch, from the calyx of Lytknmi Salicaria. Ob- 

 servations are yet wanting to determine how far the sphsei'aphid- 

 tissue may be characteristic of difi'erent orders. 



Distribution of Raphides. — This is a subject, independently of 

 its physiological interest, well deserving the attention of system- 

 atic botanists. Among Dicotyledones, raphides are not so widely 

 distributed as sphseraphides, and certainly occur so regularly and 

 plentifully in some plants, and sparingly or not at all in others, 

 as to afford good characters by which certain orders may be 

 readily distinguished from their allies of other orders, even by a 

 minute fragment of the leaf alone, and at any period of its growth, 

 which we have already exemplified ('Annals,^ May 1861 ; Jan., 

 April, and July 1863) in Onagraceee and Hubiacese. Probably 

 Balsaminaceaj and Cucurbitacese may be similarly characterized ; 

 but my examination of these orders and their allies is not yet 

 complete. The orders allied to Vitacese must also be further ex- 

 amined, as I find that both the Grape-vine and Virginian creeper 

 are true raphis-bearing plants. So are some Monocotyledones, 

 as Asparagaceffi, Aracese, Orchidacese, and part of Liliacese. In 

 all the British Typhacese raphides also occur, — which is now 

 noted because a remark to a contrary effect was in a former 

 paper (' Annals,^ Jan. 1863, p. 15), by my mistake, repeated from 

 the preceding paragraph to the species of Typha. 



Site of Raphides. — Though raphides are commonly described 

 and depicted as contained within the cells of the leaf, and I have 

 inadvertently so mentioned them in Onagracece ('Annals,^ July 

 1863, p. 53), they are often not so situated. It was shown, in 

 the 'Annals^ for May 1861. that raphides are clearly distinguish- 

 able within the cells of Lemna trisulca, and that they are longer 

 than the cells of L. minor. In many other plants it is certain 

 that the raphides do not lie within the leaf-cells, such is the dis- 

 proportion between them ; for instance, in Circaa lutetiana the 

 length of a bundle of raphides is often at least fifteen times 

 the diameter of the leaf-cell. As to a special raphid-cell and 

 cystolith, the article in the ' Micrographic Dictionary^ should 

 be consulted. 



Crystal Prisms of Iridacea. — As is well knowp, the raphides 



