STRUCTURE OF SEED-COATS. 433 



Seeds, as those of Sphenogyne speciosa and Lophospermxim eru- 

 bescens, possess wing-like appendages ; but the most remarkable 

 development of these organs is said by Mr. Quekett to exist in 

 a seed of Calosantkes Indica, an East Indian plant, in which 

 the Wing extends more than an inch on either side of the 

 seed. — Some Seeds are distinguished by a peculiarity of form, 

 which, although readily discernible by the naked eye, becomes 

 much more striking when they are viewed under a very low 

 magnifying power ; this is the case, for example, with the Seeds 

 of the Carrot, whose long radiating processes make it bear, under 

 the Microscope, no trifling resemblance to some kinds of Star-fish ; 

 and with those of Cyanthus minor, Avhich bear about the same 

 degree of resemblance to shaving-brushes. In addition to the 

 preceding, the following may be mentioned as Seeds easily to be 

 obtained, and as worth mounting for opaque objects: — Anagallis, 

 Anethum grareolens, Begonia, Carum carui, Coriopsis tinctoria, 

 Datura, Delphinium, Digitalis, Elatine, Erica, Gentiana, 

 Gesnera, Hyosciamus, Hypericum, Lepidium, Limnocharis, 

 Linaria, Lychnis, Mesembryanthemum, Nicotiana, Origamme 

 onites, Orobanche, Petunia, Reseda, Saxifraga, Scrophularia, 

 Sedum, Sempervirum, Silene, Stellaria, Symphytum asperrimum, 

 and Verbena. The following may be mounted as transparent 

 objects in Canada balsam : — Drosera, Hydrangea, Monotropa, 

 Orchis, Parnassia, Pyrola, Saxifraga.* The Seeds of Umbel- 

 liferous plants generally are remarkable for the peculiar Yittoz, 

 or receptacles for essential oil, which are found in their coats. 

 Various points of interest respecting the structure of the Testa? 

 or Envelopes of seeds, — such as the Fibre-cells of Cobcea and Col- 

 lomia, the Stellate cells of the Star- Anise, and the densely- 

 consolidated tissue of the 'Shells' of the Coquilla-nut, Cocoa-nut, 

 &c. , — having been already noticed, we cannot here stop to do more 

 than advert to the peculiarity of the constitution of the Husk of 

 the Corn-grains. In these, as in other Grasses, the Ovary itself 

 continues to envelope the seed, giving a covering to it that sur- 

 rounds its own testa: this covering (which forms the 'bran ' that 

 is detached in grinding) is composed of hexagonal cells of remark- 

 able regularity and density ; and these are so little altered by a 

 high temperature, as still to be readily distinguishable when the 

 grain has been ground after roasting, — thus enabling the Micro- 

 scopist to detect even a small admixture of Eoasted Corn with 

 Coffee or Chicory, without the least difficulty, -f- 



* These lists have been chiefly derived from the " Micrographic Dic- 

 tionary." 



t In a case in which the Author was called-upon to make such an in- 

 vestigation, he found as many as thirty distinctly -recognizable fragments 

 of this cellular envelope, in a single grain of a mixture consisting of 

 Chicory with only 5 per cent, of roasted Corn. 



P F 



