150 Parkin. — On some points in the 
Tritoma Uvaria . In this plant none of the ordinary 
mucilaginous raphide-cells could be found either in the root, 
stem, or leaf; but the other kind are numerous, varying 
considerably in size, from 60 to 160 ju. in length. The 
crystals, which almost fill each sac, are fairly abundant. 
Nuclei and protoplasm can also be made out in them (Figs. 
1 1 and 1 2). 
Polianthes tuber osa. The tuber only has been examined, 
and in it are found both kinds of crystal- cells. • The muci- 
laginous ones are more numerous and larger (Fig. xo). The 
others occur chiefly near the vascular bundles (Figs. 8 and 9). 
From the fact that these two kinds of crystal-sacs occur 
in the same plant and even in the same tissue, it looks as 
if they may have arisen independently, and not have been 
derived the one from the other. Nevertheless the above 
instances suggest that as the raphide-cells decrease in number 
their place is taken by the other type. 
In the order Iridaceae raphides seem wholly wanting, only 
the solitary crystals being present. Besides species of Iris , 
I have observed these prisms in the genera Crocus , Spar axis, 
Schizostylis , Xiphium , Freesia , Babiana , Gladiolus , and Mont- 
bretia ; and thus they appear characteristic of the order. 
It may be that the non-mucilaginous crystal-sacs discovered 
in Funkia , Convallaria , Phormium , Tritoma , and Polianthes 
are genetically connected with one another and with those 
of the Iridaceae. 
The distribution of special crystal-cells in the large petaloid 
family, the Liliiflorae, is instructive. The tribes Tulipeae 
and Allieae are exceptional in containing none 1 . They seem 
very scarce in the Colchicaceae ; Veratrum possesses a few 
raphide-cells, but I failed to find any in Colchicum or 
Uvular ia. The Iridaceae, as previously shown, possess the 
large solitary needles. The other groups, as far as I know, 
contain the ordinary mucilaginous raphide-cells, such as the 
Hyacintheae, Anthericeae, Yuccoideae, Hemerocallideae, 
1 De Bary, loc. cit. p. 142. 
