48 LABORATORY EXERCISES. 



and invert in a bottle of water, adding red ink 

 as in A above. The experiment will be more 

 striking if the level of the liquids in the two 

 experiments is the same. 



1. What is the level of the liquid within the 



second thistle-tube at the end of twenty- 

 four hours? Take measurements as in 

 the preceding experiments. 



2. Test the water in the bottle with iodine. 



What is the result and what do you con- 

 clude ? 



3. In what respects are the two experiments 



(A and B) alike? How do they differ? 



4. Why, therefore, is it necessary that starch 



be changed to sugar before it can be used 



in the body? 



C. Prepare a third thistle- tube in the same manner 

 as in A and B, except that raw white of egg 

 should be used instead of sugar or starch. 



1. At the end of twenty -four hours determine 



by measurement the height of the liquid 

 in the thistle-tube. 



2. Test the water in the bottle by boiling it 



and then testing it with nitric acid and 

 ammonia. What is the result? 



3. In what respects are the three experiments 



alike? How do they differ? 



4. (Protoplasm always contains water and al- 



bumin.) Explain why the protoplasm 

 of cells can absorb liquid nourishment. 

 Can protoplasm soak out of cells ? Give 

 reason. 



