CHORD ATA 319 



symmetry as completely as the external? How do you account for the fact? 

 Compare the relative position of the anterior and posterior appendages in as many 

 species of fish as you can secure? What are the habits of the species you have 

 been studying? Feeding habits; spawning and breeding habits? What are its 

 nearest relatives among the fishes? 



E. Studies in Nature. — Many most interesting and instructive problems present 

 themselves for the student of fishes in their native haunts, if the school is favorably 

 situated. What species are found in the nearby waters? How do they differ in 

 appearance? How in habits of feeding; of swimming; of spawning? What kind 

 of habitat does each prefer? What knowledge must a successful fisherman of a 

 given species have? 



342. The Frog. {Rand). — Any species of frog will serve. 

 For internal anatomy as large specimens as possible should be 

 used. The frog is especially suitable to represent the verte- 

 brates because of its metamorphosis from a water-breathing 

 or fish habit into the air-breathing condition, and the readiness 

 with which the main facts of this metamorphosis may be fol- 

 lowed even by an elementary class. Frogs may be kept alive 

 almost indefinitely, even through the winter, by putting them 

 in a deep box covered with netting, in which a pan of water 

 is placed. The bottom of the box should be covered by sod 

 or moss which must be kept moist. Change the water in the 

 pan every few days. Do not place large and small frogs in 

 the same box, as the small ones are more than likely to disap- 

 pear. Unless living animals, as grasshoppers and the like, 

 can be given them it is scarcely worth while to try to feed 

 them. They seem to do quite as well without food for a 

 reasonable length of time. 



A. The Living Animal (chiefly physiology). — One or more 

 exercises may well be given to observation of frogs in their 

 native haunts, if the study comes at such time as will allow. 

 You will know enough about the frog to set for discovery a 

 number of interesting things. Keep careful notes of all your 

 questions and your discoveries. If field study is not possible, 

 much can be gained by studying living specimens in the labora- 

 tory. Record what you know from observation of the animal's 

 general haunts and habits. To what extent is it a terrestrial 

 animal ? Aquatic ? What is the natural position when at rest ? 

 What are its modes of locomotion on land ? Place on the floor, 

 and test. Describe its motions in water, and the use made of 



