180 LECTURE VII. 



therefore only observed in certain transitional stages, 

 which must be exactly hit upon, in the destruction of 

 blood-corpuscles. The well-developed forms in man are 

 perfectly rectangular bodies ; but very frequently they 

 are extremely small, and nothing is seen but simple 

 spicules which shoot up into the object at certain spots 

 in large masses. There is besides this peculiarity about 

 them, that they retain the property which hgematine 

 itself has of becoming bright red with oxygen and dark 

 red with carbonic acid. It is still, however, a frequent 

 subject of discussion whether their whole substance is 

 composed of colouring matter, or whether in this case 

 also the crystals are really colourless and merely impreg- 

 nated with pigment this much, however, may be regarded 

 as certain, that the colour has something very character- 

 istic about it, and that the existence of a close connec- 

 tion between it and the ordinary colouring matter of the 

 blood cannot be doubted. 



If we now revert to the natural morphological ele- 

 ments of the blood, we meet with the colourless corpus- 

 cles as its third constituent. They are present in compa- 

 ratively small quantity in the blood of a healthy man. 

 To three hundred red corpuscles we reckon about one 

 colourless one. As they generally present themselves in 

 the blood, they are spherical corpuscles, which are some- 

 times a little larger, sometimes a little smaller than, or 



of the same size as, ordinary 

 red blood-corpuscles, from which 



are however, strikingly 

 distinguished by the want of all 

 colour and by their perfectly 

 spherical form. 

 In a drop of blood which has become quiet, the red cor- 



Fig. 56. Colourless blood-corpuscles from a vein of the pia-mater of a lunatic. 

 A. Examined when fresh ; a in their natural fluid, b in water. B. After the addi- 



