LETTERS TO BROTHER JOHN. 127 



of the body, and to the production or secretion 

 of the several juices ; such as, the gastric, the pan- 

 creatic, &c. 



The black blood, then, having been exposed, in 

 the air-cells of the lungs, to the action of the air, 

 and having been, by it, purified, re-impregnated 

 with nutritious particles, and every way requalified 

 to fulfil its appointed offices in the body, is col- 

 lected into four veins, called the "pulmonary veins"; 

 by which it is brought back to the left side of 

 the heart, from which it first started. And thus 

 the lesser circle of circulation has been accom- 

 plished, and the whole circulation of the blood 

 completed. 



Allow me to recur, for a moment, to the meta- 

 phor of the bees. I like it : it is a little fanciful, 

 perhaps, but nevertheless appropriate, and not 

 inelegant. 



Consider the lungs, then, as a bed of sweet 

 flowers, upon which a swarm of bees (the little black 

 streamlets of blood) have settled. These bees, 

 having laden their thighs with honey, quit the 

 flowers, and, taking their flight through the garden- 

 gate (the heart), pursue their way, by various 

 routes (the arteries), in order to deposit their little 

 burdens, and distribute them equally throughout 



