November 21, 1913] 



SCIENCE 



725 



rible names, and with large numbers of 

 them; some have as many as ten or even 

 fifteen different names, perhaps on the 

 Soeratic principle, that naming saves so 

 much thinking. And they are in Latin, 

 too, so that the terminology of this subject 

 is a perfect museum of long Latin and 

 hybrid-Latin names. The terminology 

 generally of our later biology is, as one has 

 said, "the Seylla's cave which men of sci- 

 ence are preparing for themselves, to be 

 able to pounce out upon us from it, and 

 into which we can not enter." This will 

 be my excuse if I should use words you do 

 not understand. 



I will just remind you of the structure 

 of the blood, that it consists of an extraor- 

 dinarily complex fluid — the plasma — which 

 holds in suspension living cellular bodies, 

 called cells or corpuscles. These are of two 

 kinds, red and white corpuscles. The red 

 are by far the more numerous, and in man 

 there are about 5,000,000 of them to a cubic 

 millimeter of blood, but this number varies 

 enormously under the influence of para- 

 sites. To these red corpuscles is due the 

 red color of the blood, and they are the 

 carriers of oxygen, acquired by the aera- 

 tion of the blood in the lungs, to the tis- 

 sues. We breathe in order that they may 

 breathe, for we only care about oxygen in 

 so far as they care about it. 



The other kind of corpuscles are the 

 white, or leucocytes, and of these, in health, 

 there are about 7,500 per cubic millimeter. 

 A few years ago it was enough to know 

 that there were red and white corpuscles, 

 but now we have to know more. Through 

 the work of Ehrlich we know that there are 

 at least five different kinds of leucocytes in 

 normal blood, which I will just indicate to 

 you. 



1. Lymphocytes. — These are the smallest 

 cells, and contain a relatively very large 

 nucleus. 



2. Large Mononuclears. — These are large, 

 and are called macrophages, as they possess 

 the power of being able to absorb and 

 digest parasites and other foreign bodies. 



3. Polynuclears. — These are character- 

 ized by the irregular, moniliform aspect of 

 their nucleus, and they are called micro- 

 phages for the same reason that the large 

 mononuclears are called macrophages. 

 Both of these are also called, generally, 

 phagocytes, on account of their power of 

 ingesting and digesting foreign bodies. 



4. Eosinophiles.— These are character- 

 ized by a bilobed nucleus, and by granula- 

 tions which color deeply with eosin and 

 other acid colors. 



5. Labrocytes or Mastzellen. — These are 

 rare, and are characterized by large granu- 

 lations which stain with basic colors. 



In parasitic diseases these corpuscles are 

 profoundly modified and altered, numer- 

 ically and morphologically, and other new 

 elements may make their appearance in the 

 blood. 



The blood is essentially the same in all 

 animals, but it varies within certain limits. 

 For instance, the red corpuscles are not of 

 the same size and shape in every animal, 

 and in birds and fishes they are nucleated ; 

 in us they are only nucleated in foetal life 

 and in disease. The mononuclear and 

 polynuclear leucocytes are really separate 

 organisms living in us, and they have 

 qualities which it is very difficult to call 

 anything else but consciousness; so that it 

 is a subtle distinction to draw the line be- 

 tween the parasites — which these leuco- 

 cytes are, in a way — which are part of us, 

 and those that are not. "When the balance 

 of power is well preserved amongst our 

 leucocytes, when they are working well 

 together, then all % well with us; if we 

 are ill, it is because they are quarreling 

 with themselves or with an invader, and 



