O ZOOLOGY. 



value concerning animals. Later many facts of general anat- 

 omy were discovered in connection with the study of medicine, 

 and about 1600 the invention of the microscope opened up the 

 field of histology. Toward the end of the seventeenth century 

 an effort was made to establish a scientific classification of 

 animals. Since that time very much of the attention of stu- 

 dents of zoology has been turned in this direction. During 

 the last century however there has been a constantly increasing 

 interest in the study of embryology, of histology, and in the 

 general theoretical questions, the answers to which depend 

 on the bringing together of the results of studies in all depart- 

 ments. Such are the problems of race development or evolu- 

 tion, of heredity, of man's place in nature, and the like. The 

 most notable development of the subject in recent years has 

 been in connection with the study of the finer structure of the 

 cell, in more exact methods of studying physiology, and in 

 extending its scope to take in the lower organisms as well as 

 the higher and the single cell as well as the organs. It is 

 important to add that all this work is now being done in a 

 comparative way. The necessity of comparing the histology, 

 the embryology, and the physiology of one animal with that 

 of another arises from the belief in the unity of animal life, 

 and that all animals are really akin. If animals of different 

 kinds are really related, their likenesses and differences take on 

 a new meaning to the student, and classification comes to ex- 

 press the degree of kinship, as well as to serve the convenience 

 of the investigator. 



1 1 a. Practical Exercises. By reference to text-books ar- 

 range a list of the most important zoological discoveries, by 

 centuries. What great contributions were made by the follow- 

 ing men? Harvey; the Janssens; John Ray; Linneus; La- 

 marck; Cuvier; Schleiden; Schwann; von Baer; Charles 

 Darwin ; Wallace ; Louis Agassiz ; Huxley ; Weismann. When 

 and where did these scientists live? Mention five American 

 zoologists and indicate their chief work. 



