86 



BIOLOGY AND ITS MAKERS 



mammals circular. He reserved the term ' globule ' for 

 those of the human body, erroneously believing them to 

 be spheroidal. 



Other Discoveries. — Among his other discoveries bear- 

 ing on physiology and medicine may be mentioned: the 

 branched character of heart muscles, the stripe in voluntary 

 muscles, the structure of the crystalline lens, the description 

 of spermatozoa after they had been pointed out to him in 

 1674 by Hamen, a medical student in Leyden, etc. Richard- 

 son dignified him with the title ' the founder of histology,' 

 but this, in view of the work of his great contemporary, 

 Malpighi, seems to me an overestimate. 



Turning his microscope in all directions, he examined 

 water and found it peopled with minute animalcules, those 

 simple forms of animal life propelled through the water by 

 innumerable hair-like cilia extending from the body like 



banks of oars from a galley, except that in 

 many cases they extend from all surfaces. 

 He saw not only the animalcules, but also 

 the cilia that move their bodies. 



He also discovered the Rotifers, those 

 favorites of the amateur microscopists, made 

 so familiar to the general public in works 

 like Gosse's Evenings at the Microscope. 

 He observed that when water containing 



these animalcules 

 evaporated they were 

 reduced to fine dust, 

 but became alive 

 again, after great 

 lapses of time, by the 

 introduction of water. 



Fig. 21.— Plant Cells. (From Leeu wen- He ma ^e many 



hoek's Arcana Natures.) observations on the 



