CHAP. XXVII.] THE COLOURLESS CORPUSCLES. 301 



structure may truly be assigned to it is amply proved by the change 

 of form, which it undergoes by the endosmosis of pure water, 

 which will cause it to burst and evacuate its contents, consisting 

 of nothing more than some minute granules, none of which can 

 be compared to a nucleus. So far as microscopic analysis would 

 enable us to decide this question, we should be disposed to declare 

 in favour of Mr. Jones's view ; but it seems greatly opposed by 

 two facts ; first, that in the corpuscle of the lower vertebra ta, the 

 colouring matter is contained between the nucleus and the cell- wall, 

 whereas in the mammalian corpuscle it would be contained in the 

 nucleus ; and, secondly, that this peculiarity of structure is limited 

 to one class of vertebrate animals. It receives support, however, 

 from observing the several steps of the development, for the cor- 

 puscle exhibits a stage in which a nucleus is visible (the stage of 

 coloured nucleated cell), (Fig. 179, d), and this nucleus in the very 

 large corpuscle of the elephant, and likewise in the very small cor- 

 puscle of the goat, exhibits a strict correspondence in size with the 

 perfectly formed blood-corpuscle. But here, again, we notice the 

 difficulty above referred to, that in this stage of nucleated cell, the 

 colour is found between the cell and the nucleus. It seems to us 

 that further research is required, in order to determine the exact 

 homology of the mammalian red corpuscle. 



The Colourless Corpuscles. These particles are found in all 

 kinds of blood. They are spherical bodies, destitute of colour ; 

 their structure is that of nucleated cells, the cell-membrane being 

 extremely delicate; both the cell mem- Fig. 179. 



brane and the nucleus and nucleolus are * ^ 



rendered distinct by the action of dilute 

 acetic acid, which dissolves some granules 

 which are contained in the cell. These c 



granules are external to the nucleus. f*\ jjj^ 



When they are numerous and large, the 

 nucleus is concealed by them. Corpuscles g 



of this kind, denominated granule cells &%. 



by Mr. W. Jones (Fig. 172, a, b), are 



viewed by him as constituting an earlier pu f c !jf e ( \ f t e r th whar\n n jo^s) d c r 

 stage than those in which the nucleus and j* flnSy^anSar s^te*! 6 cTnTjf 

 nucleolus are distinct, which he calls nu- 52& e ? l ^e2lnBSS38ii 



deated Cells (Fig. 179, C, d). In size the or perfect red corpuscle. 



colourless corpuscles slightly surpass the red corpuscles in mam- 

 malia, but not in the other vertebrata. They are essentially the 

 same as the nucleated particles found in lymph and in chyle. In 



