6 PEEFACE. 



elementary zoology to large classes, and everything indicated in it 

 has stood the test of class-room work many times. It will be found 

 serviceable in a laboratory that is well equipped for work, but is 

 especially designed for those high schools whose equipments are the 

 most meager and whose only hope of obtaining better facilities 

 for teaching lies in making a success of the work with the facilities 

 they already have. 



The illustrations are nearly all of microscopic objects, and the 

 only purpose in inserting them is to assist pupils that have not 

 the opportunity to use a compoundmicrosoope. 



Special attention is called to the forms of the tables of resem- 

 blances and differences, and to the demonstration of the homology 

 of the mouth parts of the grasshopper (page 66), to the treatment 

 of von Baer's Principle (page 99), to the three series (page 103), 

 and to the demonstration of rank among animals (page 167). 



Grateful acknowledgments for valuable suggestions are rendered 

 to Prof. S. A. Forbes and Dr. Frank Smith of the University of 

 Illinois, to President Howard Ayers of the University of Cincinnati, 

 and to Dr. Frank J. Hall of the Kansas City Medical College. 



