2 INTRODUCTION 



done by medical men and veterinarians, but within the past ten 

 years physiologists and biochemists in agricultural and medical 

 colleges have united in nutrition studies, undreamed in previous 

 decades. 



The Divisions of Zoology. — Systematic Zoology, or Taxonomy 

 (Gr. taxis, arrangement; nomas, law), has since the earliest days 

 engaged the attention of naturalists. In fact, for many years they 

 contented themselves with merely naming hundreds of animals. 

 Fierce battles were waged over the question of priority and much 

 time was wasted in futile arguments over species differences. In 

 1735 a Swedish naturalist, who took the Latin name of Linnaeus, 

 conceived the idea of a system of binomial nomenclature such that 

 the generic and specific names written in Latin or Greek could be 

 understood by scientists of all nations. Animals distinguished 

 only slightly from each other were placed as different species of the 

 same genus. For example, the domestic cat, the wild cat, and the 

 lion belong to the same genus, which we call Felis; the domestic cat 

 belongs to the species domestica and the lion is Felis leo. Over 



f 450,000 species of insects alone have been described. The branches 

 of Systematic Zoology include, among others, CoTpe^^alogy, the clas- 

 sification of Molluscs; Entomology, the classification of Insects; 

 Herpetology, the classification of Reptiles; Ornithology, the classi- 

 fication of Birds; and Mammalogy, the classification of Mammals. 

 From comparison of external characters, science progressed to a 

 study of internal arrangement and functions. Thus we have two 

 great divisions arising, one which deals with the form and structure, 

 being called Morphology (Gr. morphe, form; logos, discourse), and 

 the other treating of the functions of organs and parts, called Physi- 

 ology (Gr. phusis, nature; logos, discourse). 



Morphology includes Gross Anatomy (Gr. anatemno, to cut up), 

 which deals with dissection; Histology (Gr. histos, a web; logos, 

 discourse), which is the study of the structure of cells and tissues 

 usually stained by dyes; Ejnbryology (Gr. en, in; bruo, bud), which 

 traces the development of the egg; and Pathology (Gr. pathos, 

 suffering; logos, discourse), which deals with the structure of diseased 

 tissues. The study of Pathology is linked with Histology, Em- 

 bryology and Physiology. 



But Zoology is by no means confined to the study of stained or 

 preserved specimens. It is not the type of subject that it was 

 termed by the Professor of Latin quoted by Conklin: "Biology 



