BLIGHT. 



82 ] 



BLOOD. 



tive, 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 

 damage which the diseases have caused to 

 crops of plants of high importance to man, 

 and also of the many curious facts in then 

 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 pretty generally 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 in- 

 vestigations into their history, is given vmder 

 the head of Parasitic Fungi. The par- 

 ticular history of the more remarkable 

 genera ^^ill be found under the heads indi- 

 cated by the capitals in the following para- 

 graphs. 



Corn-blights consist chiefly of mildew 

 (Puccinia), rust or red-robin (Uredo, 

 Trichobasis), smut, hunt or brand (Ure- 

 do, Ustilago, PoLYCYSTis),j9e/j/jer-6r«wc? 

 (Tilletia), ergot (Claviceps), &c. Cys- 

 Topus ( Uredo), attacks Cruciferous plants. 

 Mildews of pease, peaches, hops and many 

 other cultivated plants are produced by 

 species of Erysiphe. Oidium is a common 

 mildew, and is supposed in many cases to 

 be only an earlier condition of the Erysiphes. 

 BoTRYTis is another common mildew. 

 iEciDiUM forms a kind of rust, as is the 

 case with the allied Rcestelia infecting 

 pear-trees. See also Uromyces, Poly- 



CYSTIS, COL^OSPORIUM, PrOTOMYCES, 



Epitea, Phragmidium, Fusisporium, 

 ToRULA, Peridermium, Sclerotium, 



SPILOCiEA, SpH^RIA. 



BiBL. De Bary, Unters. uh. die Brandpilze, 

 Berlin, 1853, gives a copious list of the pre- 

 vious works relating to the smuts and brands, 

 in chap. 3. p. 102; Berkeley, Trans. Hori. 

 Society, Gardener's Chronicle, passim ; A. 

 Braun, Krankheiten der Ffianzen, Berlin, 

 1854 (transl. Quarterly Journal of Microsc. 

 Science, July 1854) ; Sidney, Blights of the 

 Wheat, pub. by Rel. Tract Society ; article 



Blighty in Brande's Dictionary, Penny 

 Cyclopeedia and Library of Entertaining 

 Knowledge. 



BLINDIA, Br. and Sch.— A genus of 

 DicranaceousMosses,including some Weissiee 

 and Gymnostoma of authors. 



Blindia acuta, Br. and Sch. = Weissia 

 acuta, Hedw. 



B. Stylostegium, C. 'M.\i\\.=-Gym7iostomum 

 ccBspititium, Web. and Mohr. 



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 portion, 

 containing in suspension a large number of 

 minute corpuscles, which are known com- 

 monly as the globules of the blood. 



In the Mammalia, Birds, Reptiles and 

 Fishes generally, the liquid portion, or liquor 

 sanguinis as it is called, 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 other 

 consists of perfectly colourless bodies. 



The red corpuscles are far more numerous 

 than the colourless ones, and consist of delicate 

 membranous colourless cells enclosing a red 

 liquid. In the Mammalia they assume the 

 form of circular flattened discs or discoidal 

 cells, the sides of which are de]n*essed or 

 hollowed out, so as to make them resemble 

 doubly concave lenses, with rounded mar- 

 gins (PL 40. figs. 21, 22 & 23). In the Camel 

 tribe, however, they are ellij)tical and doubly 

 convex. In Birds (figs. 24 & 25), Fishes 

 (figs. 26 & 27) 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 Cyclo- 

 stomes or lamprey family among the latter, 

 in which they are circular, flattened and 

 slightly concave, only diff*ering from those 

 of man in being somcAAhat larger; and in one 

 genus of this family, Amphioxus lanceolatus 

 (the lancelet), there are no blood-corpuscles. 

 In the Reptiles, in which they are elliptical, 

 very large and comparatively thin, the 

 surfaces of the corpuscles are rather concave 



