CHAP. II.] THE BLOOD. 123 



THE GASEOUS CONSTITUENTS OF THE COLOURED CORPUSCLES. 



In discussing the properties of oxy-haemoglobin we have studied 

 with considerable minuteness the nature of that compound, and have 

 shewn that it is produced by the union of oxygen from the air with the 

 complex molecule of haemoglobin. We have shewn that under 

 various circumstances oxygen can be expelled from its state of com- 

 bination, as when blood is introduced into a Torricellian vacuum, 

 when neutral gases such as H and N are passed through it, or when 

 CO or NO act upon it. 



Now, although the oxygen removed by these various means is de- 

 rived from the oxy-haemoglobin of the corpuscles, in that body it exists 

 in a state of actual combination in a state very different from that in 

 which a gas exists which is merely dissolved in a liquid or absorbed by 

 a solid body, so that strictly we have as little right to speak of the of 

 the corpuscles as one of their gaseous constituents as we have so to 

 designate the H or N which are essential constituents of haemoglobin. 



We may however state that which we shall in succeeding sections 

 comment upon at far greater length, viz. that of the mixed gases 

 which are given up by blood when it is heated in a Torricellian vacuum 

 and which consist of a mixture of O, CO 2 and N, practically the 

 whole of the first is derived from the dissociation of oxy-haemoglobin, 

 of which each gramme can give up as much as T28 c.c. of O (at C. 

 and 1 metre pressure). Of the carbonic acid thus obtained the greater 

 part is derived from the plasma in which it is partly dissolved and 

 partly loosely combined, a small quantity only being derived from the 

 blood corpuscles. Probably the whole of the nitrogen, obtained from 

 the blood, is held in solution in the liquor sanguinis. 



In short, if we wish to be strict in our expressions, we should say that 

 probably the only gaseous constituent properly so called,i.e.gsis not exist- 

 ing in a state of chemical combination in the corpuscles, is carbonic acid. 



SECT. 5. THE COLOURLESS CORPUSCLES OF THE BLOOD. 



In addition to the red corpuscles, which have been already described, the 

 blood of vertebrate animals contains a number of globules and particles of 

 various sizes and characters, all included under the designations of white 

 corpuscles and intermediate corpuscles. 



The members of the first class are readily defined. They are nucleated 

 masses of protoplasm destitute of any cell-membrane, and containing fine or 

 coarse granules. They were first discriminated from the red corpuscles by 

 Hewson : and they were for a long time spoken of as lymphatic 

 corpuscles. In man they have a diameter of about 10 /* (^-^j in.), 

 while in batrachians they are much larger. Their most important property 

 is, without question, that of amoeboid movement, which was first observed 

 by Wharton Jones 1 in the blood of the skate. The recognition of the 

 power of amoeboid movement of white blood corpuscles was one of the most 



1 Phil. Trans. 1846. 



