PRINCIPLES OF ANIMAL BIOLOGY 39 



C. BROODING HABITS 



5. The Habit, Among Oviparous Forms, of Guarding the Eggs Without 

 Incubating Them. 



5a. Read the section in the text-book describing this habit. 



56. Examine the demonstration specimens, or in the absence of these 

 the figures of the marsupial frog (Nototrema) and a fish which carries 

 the young (Hippocampus), noting the position of the brood pouch. 



6. The Habit of Brooding the Eggs (Incubation) and the Habit of Brood- 

 ing the Young. 



6a. Read the section in the text-book describing these habits. Ex- 

 amine the series of bird and mammal nests in the laboratory, and describe 

 at least three nests representing different types of construction. 



66. Note the position of the brood pouch in a marsupial (opossum), 

 or in the figures of a kangaroo in the text-book. 



D. BIRTH STAGES 



7. Oviparous and Ovoviviparous Species with a Larval Period. 



Compare the young and adult of the common lamprey, a frog and the 

 salamander Ambystoma tigrinum. Describe the differences in the mouth, 

 eyes, form of body and appendages. 



8. Species Without a Larval Period. 



Compare the newly born young of a shark, a garter snake, two birds 

 (English sparrow and the chick), a mouse and a guinea pig. Describe the 

 differences in the stage of development at time of birth as shown by 

 the relative size, strength, the covering of scales, hair or feathers, and 

 the eyes. 



E. SUMMARY 



Do you discern any possible relation between the oviparity, ovovivi- 

 parity or viviparity of an animal and the number of eggs it produces? 

 Any relation of the same three phenomena to the certainty that the eggs 

 will be fertilized? Any relation to the mode of life of the animal? Dis- 

 cuss these relations if they appear to exist. 



