PROBLEM 199 



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preserve it. We have said that blood is made, in part at least, of 

 digested foods. In the bottle containing the clotted blood notice 

 the solid part, the clot, and a yellowish liquid called serum. 



Pour off some of the serum into each of three test tubes. 



Test the first with iodine solution. — Result? 



Test the second with Fehling's solution. — Result? 



Test the third with nitric acid and ammonia. What is the 

 result ? 



Test some of the blood fibrin with nitric acid and ammonia. 



Observations. — Note what happens in each of the three tubes. 

 What is fibrin? 



Conclusion. — 1. What nutrients are present in blood serum? 



2. Of what is fibrin composed ? 



3. What nutrients are present in blood? 



NOTE. — The blood clot is composed in part of structures (largely protein) 

 known as corpuscles. These can better be seen in prepared specimens under the 

 compound microscope. 



Problem 199 : To study the corpuscles of the blood. 



a. In Frog 



NOTE. — Blood is composed of two principal parts, solid bodies (corpuscles) 

 and a liquid (plasma) . 



Materials. — Frogs, glass slide, cover glasses, microscope. 



Method. — Place some frog's blood on a glass slide, cover and 

 examine under a compound microscope. 

 (See figure.) 



Observations. — What are the color 

 and shape of the corpuscles that are most 

 numerous and most easily seen? These 

 are red corpuscles. 



There are other irregular-shaped cor- 

 puscles, more transparent and not so 

 easily seen. These are the colorless cor- 

 puscles. 



Conclusion. — 1. What kinds of corpuscles did you find? 



2. Are corpuscles cells f Can you prove your statement? 



Cobpusclb of Frog. 



