INDEX. 



its hollow boom considered by the vulgar as the presage 

 of some sad event ; instance of it ; its flesh greatly esteemed 

 among the luxurious ; it seldom rises but when almost trod 

 upon ; at the latter end of autumn, in the evening, its wont- 

 ed indolence forsakes it ; is -then seen rising in a spiral 

 ascent, till quite lost from the view, making a singular noise, 

 different from its former boomings ; names given to this 

 bird by the Greeks and Latins, iv. 322. 



Bivalve shells, v. 208. All the kinds hermaphrodite, yet re- 

 quire no assistance towards impregnation, 232. Particularly 

 in these shell-fish the pearls are found, 24>1. 



Blackbird, of the sparrow kind, iv. 255. Sometimes seen all 

 over white ; its eggs and nest. 260. 



Black-cap, bird of the sparrow kind, iv. 257. Prized by some 

 for its singing, and is also called the Mock Nightingale, 

 279. 



Blacks, conjectural opinion that the blacks are a race of 

 people bred from one man accidentally black ; the climate 

 a cause obvious and sufficient to produce blackness ; nothing 

 satisfactory discovered upon the cause producing it in hu- 

 man complexions ; opinion of Sir Thomas Brown upon the 

 subject, ii. 91. Whence originally their flat noses, 95. 

 Black parents have procreated two white negroes, 96. 



Bladder, birds have no bladder for urine, iv. 14:. See Fishes, 

 v. 16, &c. 



Blennius, or Blenny, description of this fish, v. 21, 120. 



Blind, such as live in countries generally covered with snow 

 become blind, ii. 31. The mole not blind, iii. 198. 



Blind-worm, its description, v. 375. 



Blood, arterial blood immediately mixed with air in the lungs 

 is of a fine florid scarlet colour? that of the veins returning 

 to the heart is of a blackish crimson hue ; whence this dif- 

 ference of colour proceeds, not well understood, i. 283. 

 The blood circulates through the bones, as through every 

 other part of the body ; Mr Belcher the first who disco- 

 vered it ; his experiment to this purpose, ii. 59. Blood of 

 the rein-deer preserved in small .casks for sauce with the 

 marrow in spring, 361. The heat of the blood in man 

 and other animals about thirty degrees above congelation ; 

 in the marmot, and other animals which sleep in winter, 

 it is not above ten degrees, iii. 159. 



Blood-hound described, iii. 15. 



Blue-bird described; its residence ; is rarely caught; its doci- 

 lity; speaks and whistles at the word of command ; manner 

 of taking it, iv. 260. 



Blue-cat described, ii. 397. 



Blushing, whence it proceeds, i. 4-21. 



Boar, wild, varies not his colour as hogs of the domestic kind ; 

 description ; he plows the ground like a furrow ; his tusks 



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