HISTORY OF ZOOLOGY 43 



first natural system of classification, and it is known as the Binomial 

 System of Nomenclature. Each individual not only fits into larger 

 general groups by this sj'stem, but it is specifically known by the 

 genus and species names used together, hence the two names. Lin- 

 naeus is said to have classified and listed 4,378 species of plants 

 and animals. 



Almost immediately following Linnaeus came the Frenchman, 

 Lamarck (1744-1829), who among other important things is credited 

 with being first to realize that there are different lines of descent 

 and that no living species is absolutely fixed. Much later, in 1866, 

 Ernst Haeckel organized the modification of this system as used 

 in modern times. 



Georges Cuvier (1769-1832) is credited with establishing the field 

 of comparative anatomj^ He was of French ancestry and largely 

 self-educated by his studies at tlie seashore. A number of anatomi- 

 cal structures bear his name. 



Karl Ernst von Baer (1792-1876), a Russian biologist, is one who 

 really established embryology as a field of study. His notable paper 

 on the development of the chick was published in 1832. He estab- 

 lished the "germ layer theory,*' thus explaining the unfolding and 

 differentiation of the various organs of the developing animal. The 

 recapitulation theory, Avhich is explained elsewhere, came as a result 

 of his work and thought. 



Johannes Miiller (1801-1858), a German scientist, is referred to 

 as the founder of comparative physiology and the first to apply the 

 facts of physics and chemistry to living protoplasm. His work was 

 a great impetus to modern physiology. 



Matthias Schleiden (1804-1881) and Theodor Schwann (1810-1882) 

 are the two Germans who in 1838-1839 arrived at one of the most 

 important generalizations of biology, the cell theory (principle). 

 This is to be discussed further in the following chapter. 



Louis Agassiz (1807-1873) is commonly regarded as the father of 

 American zoology and a renowned student of comparative anatomy. 

 His great inspiration has permeated through his students to nearly 

 every institution in the land. He was a recognized paleontologist 

 as well as zoologist. He is responsible for one of our first and oldest 

 Marine Biological Laboratories. 



