192 SCIENTIFIC NOTES. 



that of exogens, because in the former the veins are parallel, and not 

 reticulated, as in the latter ; therefore, in order to separate the fibres it 

 is simply necessary to pass them between rollers. It is stated, however, 

 that the per-centage of clean fibre yielded by the grass-wrack if vary 

 small — scarcely more than a few pounds to the ton, and if such should 

 prove to be the case, however cheaply the material may be separated, in 

 a commercial point of view the operation can scarcely be remunerative. 

 But should such even prove to be the case, the question of the strength 

 of the fibre and its adaptation for dyeing and printing yet remain to be 

 tried before we can reckon much upon its adoption as a substitute for 

 cotton. 



It may be well to bear in mind that the structure of cotton differs 

 entirely from that of the fibre of the grass-wrack and of all other woody 

 fibres. The structure of cotton is identical with that of the hairs found 

 upon various parts of plants, yet even the silk cottons which resemble 

 cotton in this respect have hitherto proved of no commercial importance, 

 although the material is abundant and cheap. The silky down of tbe 

 Bombax is spun in Africa, and stockings made from it were exhibited 

 at a recent fair held in Liberia. In Zanzibar this substance is a favourite 

 substitute for cotton, and costs about half the price. The down from 

 various species of Bombax and other plants has also been spun and 

 woven in the East Indies, in several parts of America, and in some other 

 places, but the shortness of the staple and its elasticity prevent its being 

 spun by the machinery in use in this country. 



The grass-wracks are marine plants and very abundant — the scientific 

 name (Zostera) has reference to the girdle-like appearance of the long 

 linear foliage. This order of plants is very interesting, as affording the 

 stepping-stone between the flowering and the flowerless plants, yet even 

 to eyes little practised in such matters the superiority of Zostera in point 

 of organisation to the common sea-weeds of our coast has been suffi- 

 ciently apparent to give rise to a popular myth mentioned by the late 

 Hugh Miller. Directly opposite the town of Cromarty are a series of 

 sand-banks partially uncovered at spring tides, and green with Zostera 

 marina ; these are pointed out as the meadows of the old town which 

 was swept away by the encroachments of the sea some two or three 

 hundred years ago. The fishermen of the neighbourhood affirm that 

 these sand-banks are still covered with what were the luxuriant terrestrial 

 grasses of ancient Cromarty — that they are in fact essentially the same, 

 only they have made a virtue of necessity under their altered circum- 

 stances, settling down into grasses of the sea, but that they are not at all 

 akin to the brown kelp or tangle which every boisterous north-east wind 

 heaps along the coast. This is quite an inverse Darwinian theory. 



The grass-wrack can claim for itself a most remote ancestry. Hugh 

 Miller has given an engraving of a fossil plant closely allied to Zostera 

 from the trilobite-bearing schists of Giruan — associated with graptolites 

 of the Lower Silurian type. In order to appreciate in any adequate 

 degree the extreme remoteness of the geological period named, we must 

 bear in mind that since that epoch, rocks about 37,000 feet in thickness, 

 have been deposited for the most part as the sediment of long-since dried 

 up rivers, estuaries, and seas. This 37,000 feet of vertical thickness is 

 no blank record, but bears upon its ample pages full testimony that 

 during its accumulation, species, genera, and even entire orders of plants 

 and animals have been summoned into existence, and have passed away, 

 never to re-appear as living species ; and this has taken place, not once 

 only, but again and again, since that little Zostera-like plant fringed the 

 shore of the Silurian sea ; — who may say how many ages since ? 



Salislauy. EDWARD T. STEVENS. 



