68 Mr. KiPPiST on the existence of Spiral Cells 



for which I am indebted to the kindness of Mr. Brown, being from the banks 

 of the Congo. In all three the structure of the testa and its appendages is very 

 similar to that of Acanthodium, but differs in the following particulars : — 



First. The testa is less transparent than in Acanthodium, the cells being 

 formed of thicker membrane, smaller, and more nearly filled with dark 

 grumous matter, and the cells surrounding the bases of the hairs are precisely 

 similar in form to the rest, not elongated, as m Acanthodium. Secondly. The 

 hairs consist of a larger number of tubes (sometimes amounting to fifty), which 

 are quite cylindrical, not compressed, of nearly equal diameter throughout their 

 whole length, and containing a thicker and more loosely coiled spiral fibre. 

 This fibre is very generally single ; and instead of being reticulated in the 

 coherent portions of the tubes, it either continues spiral, or is disposed in 

 distinct rings, which are separated from each other by an interval of four or 

 five times the width of the fibre ; whereas in Acanthodium the coils are usu- 

 ally quite contiguous. The species diflfer from each other only in a few unim- 

 portant particulars, chiefly in the size and number of the tubes composing the 

 hairs, which are smaller and more numerous in Blepharis molluginifoUa than 

 in either of the others. In B. ruhiifolia they appear to me to be rather larger, 

 and occasionally, but very rarely, contain two spiral fibres. 



Although the fasciculated hairs already described are, as we have seen, of 

 rare occurrence in Acanthacew, many species of that family have their seeds 

 abundantly supplied with appendages, which, notwithstanding that they do 

 not adhere together, are evidently of the same nature. The most common 

 form of these appendages is that of subulate tubes or hairs, usually so closely 

 appressed as not to be perceptible upon the dry seed, but expanding in water, 

 and often discharging abundance of mucilage from their extremities. They 

 are very generally furnished with an internal fibre, which is disposed either 

 in a spiral manner, or in distinct rings, and both forms frequently occur in 

 the same tube. They sometimes occupy the entire surface of the seed, some- 

 times they are confined to its margin. Examples of spiral hairs covering the 

 entire surface are afforded by many species of Ruellia. In R.formosa the 

 hairs are short, thick and blunt, shaped somewhat like icicles; and the fibre, 

 which is always simple, usually takes an annular form, sometimes becoming 

 spiral towards the base of the hair ; those of R. strepens have the fibre disposed 



