66 ■ Mr. KiPPisT on the existence of Spiral Cells 



The fibre may be sometimes seen to divide into two in the upper part of a 

 tube, the branches usually continuing distinct; sometimes, however, after 

 making a few tnrns, they again coalesce. Towards the free extremity of the 

 tube the fibre is frequently broken up into a number of distinct rings; and in 

 other cases the spire again becomes continuous, after having been interrupted 

 by two or three such rings. In those portions of the tubes which adhere 

 together the fibre is completely reticulated ; towards the extremity, the coils, 

 though quite contiguous, are usually distinct, and readily separate by the 

 expansion of the tube ; in the intermediate parts they adhere more firmly 

 together, being connected by slender ramifications of the main fibre. The 

 expansion of the hairs in water is accompanied by a copious discharge of 

 mucilage, which makes its escape by distending and finally rupturing laterally 

 the spiral tubes in which it is contained. 



The testa, which is distinctly visible in the spaces between the hairs, consists 

 of nearly regular hexagonal cells, each containing an opake mass of grumous 

 matter, which, not filling the entire cavity, leaves a wide transparent border. 

 Cells similar to these, but more elongated and gradually passing into the form 

 of tubes, immediately surround the base of each hair, which appears to be filled 

 up by a conical mass formed of the transparent tubular portions. 



The seeds brought home by Mr. Holroyd unquestionably belong to a spe- 

 cies oi Acanthodium, and were at first considered by Professor Don to be those 

 oi Acanthodium spicatum, an opinion which seemed to be confirmed by their 

 striking resemblance to the figure and description given by Delile in the botani- 

 cal part of the great French work on Egypt* ; but having been since favoured 

 by the kindness of Mr. Brown with a seed from an authentic specimen of 



• The following is Delile's account of the seed of Acanthodium spicatum from the work above 

 quoted : — 



" Les graines sont couvertes de polls blancs, couches de bas en haut et comme coll6s, qui naissent 

 de la tunique de la graine : ces poils, lorsque Ton met la graine dans I'eau, la retiennent d'abord flot- 

 tante par I'air qui occupe leurs intervalles ; il se d^gage presque aussit&t, et la graine tombe au fond de 

 I'eau ; elle se h6risse de toutes parts par les poils qui se dressent k sa surface : les rangs de poils couches 

 sur les bords de la graine se sdparent les uns des autres et presque simultan^ment, aprfes ceux des faces 

 de la graine ; ils sont surtout longs et abondans' sur ses bords, et sont coud^s par leur extr^mit^ libre 

 que Ton voit se d6ployer dans I'eau du sommet vers la base de la graine. Ces poils mouill^s se cou- 

 vrent et sont agglutin6s par un enduit visqueux, transparent." 



