37G THE HISTORY OF I'KE SCIENCE OF ZOOLf)Gy 



connected, and made otlier histological contributions to 

 zoology. Leeuwenhoek, a Dutch investigator, discovered 

 blood corpuscles and striated muscle fibers, watched the 

 circulation of blood in the tail of a tadpole, thus confirm- 

 ing Harvey's discovery, and described man\' forms of 

 Protozoa, rotifers, and hydra' hithei'to unkno^Mi. ,S\vam- 

 mcrdam, anothei' Dutchman, is known to all entomologists, 

 for he studied and dcsciibed the habits, metamoi'phoses, 

 and anatomy of many different insects, accompanying his 

 descriptions with illustrations. Just here must be men- 

 tioned the two filnglishmcn, Hood and Gi'cw, who dis- 

 covered, in the tissues of ])lants, minute cavities filled with 

 fluid and suirounded by walls which they termed ceZ/.s'. 



Passing over othei' and lesser investigators we come to the 

 English clergyman, ,John Ray, who first systematized the 

 zo()logical knowledge already gained and put the science 

 of zoology on an organized liasis. He grasped the idea of 

 species and .saw the real value of a comparison of anatomical 

 characters of animals to show their true relationshi]5s, which 

 enabled him to classify animals much better than they had 

 been heretofore. 



Eighteenth century. — The .year 1707 saw ushered into 

 the world the S\\edi.'^h founder of modern systematic zocil- 

 ogy, Carl Linne, or fjinnanis. He first established the value 

 of groups higher than s]iecies — genera, ortlers, and classes 

 — and used them in theii- pro|ier relation to each other. 

 He also instituted the systc'm of naming animals accor(hng 

 to the i)rinci])les of the binomial nomenclature. That is, 

 each animal was given two names taken IVom the lAitin 

 language, the firsi nami^ indicating the genus and the siM'ond 

 name the species lo which the aiumal belonged. Linna-us 

 also named and described each sjiecies of animal and 



