20 COMPARATIVE ANATOMY BKFOKK (TYIKK 



For Aristotle, as for all anatomists before the days of the 

 microscope, the tissues were not much more than inorganic 

 substances, differing from one another in texture, in 

 hardness, and other physical properties. They possessed 

 indeed properties, such as contractility, which were not 

 inorganic, but as far as their visible structure was concerned 

 there was little to raise them above the inorganic level. The 

 application of the microscope changed all that, for it revealed 

 in the tissues an organic structure as complex in its grade as 

 the gross and visible structure of the whole organism. Of 

 the four men who first made adequate use of the new aid, 

 Malpighi, Hooke, Leeuenhoek, and Swammerdam, the first- 

 named contributed the most to make current the new 

 conceptions of organic structure. He studied in some detail 

 the development of the chick. He described the minute 

 structure of the lungs (1661), demonstrating for the first time, 

 by his discovery of the capillaries, the connection of the 

 arteries with the veins. In his work, De visccruin stnictnra 

 (1666), he describes the histology of the spleen, the kidney, 

 the liver, and the cortex of the brain, establishing among 

 other things the fact that the liver was really a conglomerate 

 gland, and discovering the Malpighian bodies in the kidney. 

 This work was done on a broad comparative basis. " Since 

 in the higher, more perfect, red-blooded animals, the 

 simplicity of their structure is wont to be involved by many 

 obscurities, it is necessary that we should approach the 

 subject by the observation of the lower, imperfect animals." 1 

 So he wrote in the De I'isccniin structure, and accordingly he 

 studied the liver first in the snail, then in fishes, reptiles, 

 mammals, and finally man. In the introduction to his 

 Aiuiloiiic plantarntn (1675), in which he laid the foundations 

 of plant histology, he vindicates the comparative method in 

 the following words : " In the enthusiasm of youth I applied 

 myself to Anatomy, and although I was interested in par- 

 ticular problems, yet I dared to pry into them in the higher 

 animals. But since llu-M- matters enveloped in peculiar 

 mystery still lie in obscurity, the}' require the comparison 

 of simpler conditions, and so the investigation of insects'-' 



1 Trans, by Foster, loc. cit., p. 1 13. 



- He made a careful studv of the silkworm. 



