No. 387.] THE PRESENT STATUS OF ANATOMY. 189 
covery by Harvey of the circulation of the blood, a discovery 
which marked a second great epoch in the history of anatomy. 
It laid the axe at the root of the spiritual theories prevalent 
at the time, which recognized as the essence of life an unknown 
something, the spzvztus or aura, which, being confected in the 
liver, served to distend the heart, whence it was distributed as 
a spiritus naturalis by the veins to certain organs of the body, 
and as a spiritus vitalis to others by the arteries. Harvey’s 
discovery necessarily proved a serious blow to such vague 
ideas, though in one form or another they continued to exist 
for nearly two centuries, the sfzritus being a ghost difficult to 
lay. Harvey showed that the heart was not passive, but was 
a muscular pump, that the heart and not the liver was the 
starting point of the circulation, that the blood of the arteries 
and of the veins was the same, and that the course of the 
blood in both sets of vessels was in a definite direction. And 
by so showing he laid the foundation stone of our modern 
science of physiology. 
But the seventeenth century is entitled to the credit of lay- 
ing the foundation stone not only of physiology, but also of 
microscopical anatomy and of comparative anatomy. Leeu- 
wenhoek, polishing his own lenses and subjecting to their 
action whatever came to his hand, made many important dis- 
coveries, chief among which appear bacteria, the yeast plant, 
and spermatozoa ; and Malpighi discovered the blood corpuscles 
and completed the missing link in Harvey’s scheme of the cir- 
culation by describing the capillaries by which the veins and 
arteries are placed in communication. 
The interest awakened in human anatomy in the sixteenth 
century was not accompanied by an equal interest in the study 
of the lower forms, but towards the close of the seventeenth 
century comparative anatomy was again called to the aid of 
human anatomy by Nehemiah Grew, by Tyson, who availed 
himself of an opportunity for dissecting an ourang and care- 
fully compared its structure with that of man, and by Collins, 
who with Tyson’s aid illustrated the structure of the human 
body by references to the peculiarities of structure found in 
the lower animals. 
