CONSTITUENTS OF THE BLOOD-CORPUSCLES. 185 



for it is believed that the capsule of the colourless corpuscles, from 

 which the coloured cells at all events in part proceed, retains for 

 some time its former chemical nature, even when pigment has 

 become formed within the cell. The cell-wall, which so rapidly dis- 

 appears from our sight under the microscope, is, however, actually 

 dissolved by very few of these reagents ; it only passes into a 

 gelatinous or rather a mucus-like condition, in which its coefficient 

 of refraction is nearly the same as that of the plasma ; we arrive 

 at this conclusion not merely from the experiment to which refer- 

 ence has been frequently made, by which the cell-wall may again 

 be rendered visible either in all its integrity or at all events in 

 fragments by solutions of salt, iodine, &c., but also from the 

 viscidity and tenacity which are imparted to the blood by the 

 addition of certain substances, as dilute organic acids, alkaline 

 carbonates, iodide of potassium, hydrochlorate of ammonia, &c. 

 If blood which has been thus modified be saturated with acids or 

 alkalies, or if a solution of iodine or of sulphate of soda be added 

 to it, the walls of the corpuscles again become apparent, and the 

 blood at the same time loses its acquired viscidity. Moreover 

 neither the intercellular fluid nor the serum is reduced by the 

 above means to such a viscid or tenacious condition, which must 

 therefore be dependent on the blood-corpuscles : further, mucus 

 which had become swollen in water becomes condensed by the 

 same means, so as to be less transparent to the unaided eye, 

 appearing almost as if it were coagulated, and exhibiting thread- 

 like streaks under the microscope. 



The globulin, or coagulable matter contained in the blood-cells, 

 as well as the hcematin, has been fully considered in the first 

 volume ; we shall therefore direct our attention to the other organic 

 substances which must be regarded as essential constituents of the 

 coloured cells. 



With regard to the nuclei of the blood-corpuscles, in a morpho- 

 logical point of view they are of very doubtful importance, since 

 several of our first physiologists (R. Wagner amongst the number) 

 regard the very distinct and often clearly defined nuclei of the 

 blood-corpuscles of the amphibia as products of chemical secretion 

 from the homogeneous cell-contents after death, while others 

 conceive that in the discoid coloured bodies in the blood of mam- 

 malia and birds they see the nuclei or their remains. But whatever 

 decision may be arrived at regarding the morphological existence 

 of these elements, nothing can as yet be definitely concluded 

 regarding their chemical nature, in the first place because we are 



