THE GROWTH AND SCOPE OF BIOLOGY 11 



loaned one. Everything that could be observed with a microscope 

 became an object of his study. The biological objects included were the 

 blood capillaries, red blood cells, spermatozoa (male germ cells), striated 

 muscle, the crystalline lens of the eye, the eggs of insects, and minute 

 organisms in pond water. Another Dutchman, Jan Swammerdam (1637- 

 1680), besides some work on gross anatomy, studied the minute anatomy 

 of insects and snails and the development of the eggs of various animals. 

 Microscopes existed in America in the seventeenth century, but no 

 important use of them in biology appears to have been recorded. 



Fig. 7. — Anton van Leeuwenhoek, 1632-1723. {From Garrison, "History of Medicine.") 



Classification of Animals and Plants. — One of the early trends away 

 from structure was the series of attempts to classify living things. Efforts 

 to systematize the listing and arrangement were made in very early times 

 by Plato and Aristotle. These were very simple; Aristotle mentions by 

 name only two ranks, which correspond roughly to the species and family 

 of our present classification. When the great geographic discoveries of 

 the sixteenth and seventeenth centuries were made, and many new 

 animals became known, such simple groupings were of little use. The 

 first classification worthy of note was that of John Ray (1627-1705), 

 in England. Ray's idea of the species was very similar to that of the 

 present time. He grouped similar species into a genus, but his genera 

 were much more inclusive than at present. Anatomical likeness was the 

 basis on which species were grouped together, though he allowed old 



