BLIGHT. 



[ 100 ] 



BLOOD. 



and the species of Cynips and allied genera, 

 which produce galls and similar excrescences 

 by the irritation of the vegetable tissue, re- 

 sulting from their presence. 



Many caterpillars of moths and butterflies 

 are exceedingly destructive, and form a kind 

 of blight ; but these scarcely come within our 

 province. 



The vegetable blights, the parasitic Fungi 

 growing upon living specimens of the higher 

 plants, and displaying themselves either as 

 the cause or the accompaniment of some 

 disease and disorganization, have of late 

 years become objects of most earnest atten- 

 tion, on account both of the enormous da- 

 mage which the diseases have caused to 

 )lants of high importance to man, 



and also of the many curious facts in their 

 history which have 'been brought to light. 

 The Potato blight and the Vine disease of 

 recent years have incited renewed efforts to 

 elucidate the history of these productions, 

 as yet, however, imperfectly made out. The 

 old notion, that these products were the 

 result of skin-diseases or exanthemata of 

 plants, is now discarded, especially as many 

 of them have been grown artificially from 

 their spores. 



The general history of the conditions of 

 their occurrence, and a summary of the 

 investigations into their history, are given 

 under the head of PARASITIC IUNGU. The 

 particular history of the more remarkable 

 genera will be found under the heads in- 

 dicated by the capitals in the following 

 paragraphs. 



Corn-blights consist chiefly of mildew 

 (PUCCINIA), rust or red-robin (UREDO, TRI- 

 CHOBASIS), smut, bunt, or brand (TILLETIA, 



USTILAGO, POLYCYSTIS), 61'ffot (CORDI- 



CEPS), &c. CYSTOPUS ( Uredo) attacks Cru- 

 ciferous plants. Mildews of pease, peaches, 

 hops, and many other cultivated plants are 

 produced by species of ERYSIPHE. OIDIUM 

 is a common mildew, and is known in many 

 cases to be only an earlier condition of 

 Erysiphe. BOTRYTIS is another common 

 mildew. yEciDiUM forms a kind of rust, 

 as is the case with the allied RCESTELIA, 

 infecting pear-trees. See also UROMYCES, 

 POLYCYSTIS, COLEOSPORIUM, PROTOMY- 

 CES, EPITEA, PHRAGMIDIUM,FUSISPORITJM, 

 TORULA, PERIDERMIUM, SCLEROTIUM, SPI- 

 LOCJEA, SPH^ERIA. 



BIBL. De Bary, Brandpilze, Berlin, 1853, 

 chap. 3. p. 102 ; Berkeley, Tr. Hort. Soc., 

 Gardeners Chron., passim; A. Braun, 

 Krankheiten der Pflanzen, Berlin, 1854 ( Qu. 



Mic. Jn., July 1854) ; Sidney, Blights of the 

 Wheat, Rel. Tract Soc.; art. BtigU, in 

 Branded Diet., the Penny Cyclop. ; Libr. of 

 Entertaining Knowledge ; Boisduval, Entom. 

 Horticole ; Hallier, Phytopatholoyie. 



BLINDIA, Br. and Sch. A genus of Di- 

 cranaceous Mosses, including some Weissia 

 and Gymnostoma of authors. 



BIBL. Wilson, Bryol. Brit. p. 67. 



BLOOD. This animal fluid, with the 

 general appearance of which in the higher 

 animals every one is so familiar, is no less 

 difficult in its microscopic study, than it is 

 complex in its chemical composition. In 

 man and mammalia, birds, reptiles and fishes, 

 it is a viscid liquid of a red colour. In those 

 of the lower classes in which it exists, it is 

 mostly colourless, sometimes, however, red, 

 bluish, purplish, greenish or milky. 



When examined under the microscope 

 the blood is found to consist of a liquid por- 

 tion, containing in suspension a large num- 

 ber of minute corpuscles, which are known 

 commonly as the globules or corpuscles of 

 the blood. 



In the Mammalia, Birds, Reptiles, Am- 

 phibia, and Fishes generally, the liquid por- 

 tion, or liquor sangninis, is nearly colourless, 

 or of a pale yellow tinge ; and the corpuscles 

 are of two kinds, one of a red colour when 

 viewed in mass, but pale reddish yellow when 

 seen singly or separately, and to these the 

 red colour of the blood is owing ; the others 

 consist of perfectly colourless bodies. 



* The red corpuscles are far more numerous 

 than the colourless ones, about 500 to 1, and 

 consist of delicate membranous colourless 

 cells enclosing a red liquid. In the Mam- 

 malia they assume the form of circular flat- 

 tened disks or discoidal cells, the sides of 

 which are impressed or hollowed out, so as 

 to make them resemble doubly concave 

 lenses, with rounded margins (PI. 49. figs. 

 21, 22 & 23) ; in the Camel tribe, however, 

 they are elliptical and doubly convex. In 

 Birds (figs. 24 & 25), Fishes (figs. 26 & 27), 

 Amphibia and Reptiles (figs. 28, 29 & 30), 

 they are elliptical and flattened, the form of 

 the sides varying : thus, in Birds and Fishes 

 they are convex, excepting the Cyclostomes 

 or lamprey Order among the latter, in which 

 they are circular, flattened and slightly con- 

 cave, only differing from those of man in 

 being somewhat larger; and in the Lepto- 

 cardea Amphioxus lanceolatus, the lancelet, 

 there are no blood-corpuscles. 



In the Amphibia and Reptiles, in which they 

 are elliptical, very large, and comparatively 



