in the Seeds of Acanthacese. 71 



traversed by elevated ridges, which inclose irregular areas, often more or less 

 quadrangular in form, with a raised point in the centre: on the concave 

 surface the woody cells are frequently extended into short, rigid, slightly- 

 recurved hooks, very different from the elongated membranous hairs which 

 occur on the edge. The marginal hairs of D. erectiis sometimes contain a 

 quantity of granular niatter, and the hooks on the disc are somewhat longer 

 than in D.patulus. The seed of D.dejectus scarcely seems to differ in struc- 

 ture from those of the two species already noticed, except in having spiral 

 hairs on the border ; but the only specimen I have had an opportunity of 

 examining was very imperfect. 



In Blechum Brownei the seed is furnished with a narrow whitish border, 

 formed of short, cylindrical, membranous cells, rounded at their ends, entirely 

 destitute of fibre. These cylindrical cells are arranged in a radiating manner, 

 not appressed like the hairs which compose the border of Strobilanthes, Dipte- 

 racanthus, &c. On being moistened they become greatly distended by the 

 expanding mucilage within, and ultimately assume the form of wide, blunt, 

 wavy tubes, constructed of an exceedingly delicate membrane, without fibre 

 or any very distinct markings, and frequently terminated by a small club- 

 shaped appendage, looking something like the rudiment of a second cell. 



In a considerable number of Acanthacece the seed is invested with very 

 numerous long, slender, tapering hairs, formed of simple membrane, and pro- 

 ceeding equally from every part of the testa, closely appressed, but expanding 

 in water, without any discharge of mucilage. This structure I have found to 

 be very prevalent in the genus Barleria, having examined nine species without 

 observing a single exception ; it also occurs in many species of Lepidagathis 

 and Goldfussia, in Eranthemum* nervosum, and E. IVightianum, Phlogacanthus 

 thyrsiflorus, Hemiadelphis polysperma, and Neurostachys tetragonostachys. 



In Lepidagathis fasciculata, L. mucronata and L. hyalina, the hairs are much 

 shorter and blunt-pointed, but devoid of fibre, and scattered over the whole 

 surface of the testa, as in the majority of the species. Those of L. scariosa 



* A remarkable difference of structure occurs in the seeds of Eranthemum crenulatum, and another 

 species closely allied to E. bicolor ; the testa in both is entirely destitute of hairs, and reticulated 

 ■with anastomosing ridges formed of elongated cells ; in the areas between the elevated ridges the cells 

 are shorter and nearly hexagonal. 



