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TEXT-BOOK OF PHYSIOLOGY 



Subsequently the nucleus is extruded, carrying with it a portion of the peri- 

 nuclear cytoplasm, after which the remainder of the corpuscle assumes 

 the shape and size of the adult corpuscle and is carried out into the general 

 circulation. After severe hemorrhage the formative processes in the marrow 

 may become so active that erythroblasts and normoblasts make their appear- 

 ance in the blood-stream before the extrusion of the nucleus has taken 

 place. 



The Corpuscles of Other Vertebrated Animals. In all mammals, 

 with the exception of the camel, llama, and dromedary, the red corpuscles 

 present the same shape and structure as the corpuscles of man, and may be 

 described as circular, flattened, biconcave discs. In the animals excepted 

 the corpuscles are oval. The size, however, varies in different animals from 

 0.0092 mm. (yl^ inch) in the elephant to 0.0023 mm - (T^-ST mch) in the 

 musk-deer, while in most animals the average lies between 0.0084 m m. and 

 0.0050 mm. Inasmuch as the question may arise as to whether the corpus- 

 cles of any given specimen of blood are those of a human being or of some 



other mammal, a knowledge of the size of the 

 corpuscles is a matter of medicolegal as well as of 

 physiologic interest. Though the differences in size 

 are slight, yet it is possible for skilled^microscopists, 

 when examining fresh blood, to make a diagnosis 

 between the corpuscles of man and those of the 

 domesticated animals, with the exception, perhaps, 

 of the guinea-pig. The diagnosis of the corpuscles 

 of dried blood which have been altered by the ac- 

 AMPHIBIAN COLORED tion of various external agents, even though capa- 

 BLOOD-CORPUSCLES. Fig. ble of a certain degree of restoration, is most dif- 

 104, on the flat; Fig. 105, on ficult and should not be attempted in criminal 



edge. (Landois and ., . . r 



Stirling.) cases without large experience in microscopy, in 



measurements and methods of preparation of all 



kinds of blood-corpuscles, and a proper conception of corpuscular forms 

 and sizes. In the following table the average results of the measurements 

 of the corpuscles in different classes of animals are given (abstracted from 

 Formad's compilation) : 



FIG. 104. FIG. 105. 



* Masson. 



t Woodward. 



In birds, reptiles, and amphibians the corpuscles are larger than in 

 mammals, are oval in shape, and nucleated. (See Figs. 106 and 107.) 

 As the scale of animal life is descended the corpuscles increase in size, until 



