CHAPTER III 

 FROGS AND THEIR RELATIVES 



81. Study of the frog. Laboratory study. 



A. . Regions and appendages. The frog's body consists of 

 two principal parts, or regions ; namely, the head 

 and trunk. The line of union between the two 

 regions is just in front of the anterior append- 

 ages (arms). 



1. Locate the appendages (arms and legs) attached to 



the trunk. 



2. Name and locate the organs that you find on the 



head, giving the number of each. 



B. Breathing organs. 



1. Describe the location of the nostrils on the head. 



2. Examine a preserved specimen in which a stiff bristle 



has been passed through one of the nostrils. 



a. Tell what was done. 



b. Into what cavity has the bristle emerged ? 



c. (Optional.) What is one difference, therefore, between. 



the nostrils of a fish and of a frog ? (See 102, 2 b.) 



d. In what region (anterior or posterior) of the roof- 



of the mouth cavity are the inner openings of 

 the nostrils located? 



3. (Demonstration.) Just back of the tongue there is 



a narrow opening that leads into the windpipe 

 (trachea). This opening is called the glottis. 



a. Locate the glottis. 



b. Does the glottis extend lengthwise or crosswise 



of the mouth cavity ? 



c. Into what does the glottis open ? 



4. Examine a dissected frog prepared in such a way as 



to show the lungs. 

 101 



