Page:The Harveian oration 1903.djvu/28

 of the Worshipful Company of the Barber Chirurgions."

Moreover, the significance of the movements of the chest in breathing and of their relation to the entrance and exit of the air from the lungs was but imperfectly realised. If to Borelli may be attributed the first settlement of these questions on right lines, applying as he did to the problem the growing mechanical and chemical knowledge of his day, and showing as he did that the air entered the lungs as a result of atmospheric pressure as the chest enlarged by muscular contraction, and further that the air inspired was actually taken up by the blood, and that this was essential to the life: of the animal, all of which are the facts which are at the basis of our present knowledge of the subject—if, as I say, Borelli showed this, the way for his so doing was made clear for him by what had been done in explaining the true structure of muscular tissues and still more by the labours of his fellow Professor at Pisa, Malpighi. More than fifty years after the invention of the compound microscope, this observer applied it to the investigation of the tissues, and had himself informed Borelli of the minute structure of the lungs, how the terminal branches of the air tubes ended in closed vesicles, on the walls of which the smallest blood vessels ramified, forming the