BLOOD. 



[ 84 ] 



BLOOD. 



Birds. length, breadth. 



Chaffinch (Fringilla coe- 



lehs) 1-2253 1-4133" 



Cuckoo (Cuculus cano- 



rus) 1-2028 1-3600 



Eagle {Aquila), mean of 



four species 1-1640 1-3651 



Fowl (Gallus domesti- 



cus) 1-2102 1-3466 



Gull (Mew-, Larus ca- 



nus) 1-1973 1-3839 



Ilumming-bh'd {Tro- 



cUlus ?) 1-2666 1-4000 



Ostrich {Strut hio ca- 



melus) 1-1649 1-3000 



Owl {Strix flammea) . . 1-1882 1-3740 

 Parrot( Psittacus), mean 



of twelve species .. 1-2042 1-3/24 

 Pigeon( Columba) ,mean 



of sixteen species .. 1-2135 1-3679 

 Sparrow {Fringilla do- 



mestica) 1-2140 1-3500 



Reptiles. 



Crocodile (Crocodilus 



acutus) 1-1231 1-2286 



¥rog{Ranatemporaria) 1-1108 1-1821 

 Lizard {Lacerta vivi- 



para) 1-1660 



Siren lacertina 1-435 1-800 



Toad {Bufo vulgaris).. 1-1043 1-2000 

 Triton {Lissotriton 



punctatus) 1-830 



Fishes. 



Carp {Cyprinus carpio) 1-2142 1-3429 



Eel {Anguilla vulgaris) 1-1745 1-2842 



Jack {Esox lucius) .... 1-2000 1 -3555 

 Miller's Thumb (Co^^M5 



gobio) 1-2000 1-2900 



Ferch{Percafluviatilis) 1-2099 1-2824 



Tench {Cyprinus Tinea) 1-2286 1-2722 



The colourless corpuscles have not been 

 so extensively examined. They do not vary 

 so much in size in different animals as is the 

 case with the coloured corpuscles. Those 

 of the human blood are about 1-2500" in 

 diameter. 



The red corpuscles of blood are easily 

 altered in form by most liquids ; those of 

 less specific gravity than the liquor sanguinis 

 distend them, rendering them larger, paler 

 and more transparent, and effacing the len- 

 ticular appearance and the elliptical form 

 when present. If the liquid be added in 

 large proportion, the envelope or cell-mem- 



brane becomes extremely thin and pale, until 

 at last it is no longer distinguishable ; some- 

 times it bursts. These phfenomena are the 

 result of endosmosis. The red corpuscles 

 are not, however, all equally acted upon : 

 some are much more affected than others ; 

 some even appear almost entirely to resist 

 the action of endosmotic agents, and are 

 found but little altered, even when the blood 

 is mixed with a large proportion of water. 

 They then subside to the bottom of the 

 vessel. This has given rise to the eiToneous 

 notion that water at first renders the red 

 corpuscles larger and then diminishes their 

 size ; but the real ex])lanation is that above 

 given. Although water and other endosmotic 

 agents distend the coloured coi*puscles, and 

 render their envelopes so extremely transpa- 

 rent that they can no longer be recognized, 

 yet many of them may be restored to view 

 by the addition of reagents which either act 

 exosmotically, colour them, or render them 

 opake; as solution of iodine, of bichloride 

 of mercury, and various other salts. Many 

 of them, however, burst, and others disappear 

 entirely, apparently from being truly dis- 

 solved. 



The smallest are generally those least af- 

 fected, and these are the oldest or the most 

 perfectly developed ; for we shall see pre- 

 sently that during their earlier stages of de- 

 velopment, the coloured corpuscles are many 

 times larger than in their mature condition. 

 Dilute acids act nearly in the same manner as 

 water, but much more rapidly. Dilute solu- 

 tions of alkalies produce the same effect, but 

 soon dissolve them completely. Solutions 

 of neutral salts act exosmotically, rendering 

 them smaller, more flattened, and producing 

 wi'inkles, folds, or a granular appearance in 

 the enveloping membrane. Frequently also 

 they appear covered with httle points, giving 

 them an elegant stellate aspect. This stel- 

 late or crenate appearance is not unfrequently 

 seen immediately that fresh blood is exa- 

 mined under the microscope. Two principal 

 conditions are especially favourable to its 

 production, viz. a concentrated state of the 

 liquid, and an increase in the proportion of 

 alkaline chlorides. 



The colom'less corpuscles are much less 

 afifected by reagents. Water distends them 

 slightly, rendering their granulations less 

 distinct. Acetic acid does the same to a 

 greater extent, bringing to light the nuclei. 

 Alkalies dissolve them. When blood is mixed 

 with a large quantity of water, the mixture 

 shaken and set aside, a pale buff precipitate 



