BLE 



BLI 



bleached by the oxymnriatic acid. The 

 process succeeds best when the acid is 

 used in the state of gas. Berthollet has 

 announced a peculiar effect obtained from 

 the action of oxymuriatic acid, that of 

 giving the appearance of cotton to hemp 

 or flax. The process consists in immers- 

 ing the flax, prepared by boiling, and by 

 an alkaline solution in oxymuriatic acid 

 of a certain strength, for some time, and 

 alternating this immersion repeatedly 

 with the action of an alkaline ley. 



BLECHNUM, in botany, a genus of the 

 Cryptogamia Filices, or Ferns. There 

 are six species, all of them natives of 

 warm or hot countries, excepting B. virgi- 

 nicum, which will bear the open air of 

 England. They are increased by parting 

 the roots. 



BLENDE. See ZINC. 



BLENNIUS, blenny y in natural history, 

 a genus of fishes of the order Jugulares. 

 The generic characters are, head sloping ; 

 body lengthened, sub-compressed, lubri- 

 cous ; gill membrane six-rayed ; ventral 

 fins two, three or four-rayed, unarmed ; 

 anal fin distinct. There are two divi- 

 sions ; viz. A. head crested ; B. head not 

 crested ; and according to Gmelin there 

 are 18 species, though Dr. Shaw enume- 

 rates more. B. galerita, or crested blen- 

 ny, inhabits the European ocean, is four 

 or five inches long ; its body is brown and 

 spotted ; the skin at the corner of the 

 upper jaw loose, projecting ; dorsal fin 

 extending from the head almost to the 

 tail ; ventral fin small ; vent under the 

 ends of the pectoral fin. This fish is fre- 

 quently found about the rocky coasts of 

 Great Britain. B. ocellaris has above the 

 eyes a single ray, and on the first dorsal 

 fin a large black ocellate spot. It inha- 

 bits the Mediterranean Sea ; is eight 

 inches long ; the body is without scales, 

 dirty green, with olive streaks, rarely 

 pale blue : the flesh is eatable, but in no 

 great estimation. Although Linnaeus and 

 others have described this fish as having 

 two dorsal fins, Block considers it as hav- 

 ing in reality but one ; the sinking in of 

 the middle part being in some specimens 

 much deeper than in others, seems to be 

 the cause of this difference of opinion. 

 B. saliens is a very small species, observ- 

 ed about the coasts of some of the south- 

 ern islands, and particularly those of New 

 Britain. It seems to be of a gregarious 

 nature, and is seen swimming by hun- 

 dreds, and flying as it were over the sur- 

 face of the water, occasionally springing 

 among the rocks. It is naturally formed 

 for celerity in its movements, the pecto- 

 ral fins being very large in proportion to 



the body. They are nearly of a circular 

 form when expanded, and when contract- 

 ed reach almosi as far as the vent on eacli 

 side. B. superciliosus has a small head, 

 with large eyes, and silvery irides, and 

 immediately over each eye is situated a 

 small palmated crest, or appendage, di- 

 vided into three segments. The body is 

 covered with very small scales, and is of 

 a yellow or gilded tinge, and marked with 

 numerous and irregular spots of dusky 

 red. The dorsal tin commences at the 

 back part of the head, and is continued 

 almost to the tail ; but near its commence- 

 ment suddenly sinks, so as almost to give 

 the appearance of a smaller anterior dor- 

 sal fin, separate from the longer one : 

 the pectoral fins are of moderate size ; 

 the ventral ones didactyle, and rather 

 long ; the vent is situated in the middle 

 of the abdomen, from which part the anal 

 fin commences, and reaches as far as the 

 tail. This species is found native in the 

 Indian seas, grows to the length of about 

 twelve inches, and is viviparous. There 

 is, however, another species, denominat- 

 ed B. viviparus, which, like that just no- 

 ticed, is distinguished by a particularity 

 that takes place in but very few fishes, 

 except those of the cartilaginous tribe ; 

 being viviparous, the ova hutching inter- 

 nally, and the young acquiring their per- 

 fect form before the time of birth. Not 

 less than two, or even three, hundred of 

 these have been sometimes observe d in a 

 single fish. It might be imagined that so 

 great a number, confined in so small a 

 space, might injure each other by the 

 briskness of their motion ; but this is 

 prevented by the curious disposition of 

 fibres and cellules among which they are 

 distributed, as well as by the fluid with 

 which they are surrounded. When ad- 

 vanced far in its pregnancy, it is scarcely 

 possible to touch the abdomen without 

 causing the immediate exclusion of some 

 of the young, which are instantly capable 

 of swimming with great alertness. The 

 B. viviparus is a littoral fish, and is found 

 about the coasts of the Mediterranean, 

 and the Baltic and Northern Seas, and 

 sometimes it enters the mouths of rivers. 

 It feeds on the smaller fishes, &c. It is 

 taken by the line and net; but is not es- 

 timated as food, as its bones acquire a 

 greenish colour by boiling. See Plate II. 

 Pisces, fig. 2 



BLIGHT, in agriculture, a general 

 name for various distempers incident to 

 corn and fruit trees. It affects them va- 

 riously, the whole plant sometimes pe- 

 rishing by it, and sometimes only the 

 leaves and blossoms, which will be scorch- 



