70 NATURE-STUDY REVIEW [17:2— Feb., 1921 



5. Dirty hands show you do not belong to the refined class of 

 people. 



Milk is heated to 170" F. (pasteurized) before it is delivered to 

 city customers (Check the best reason). 



1. To kill the germs of disease that may be in it. 



2. Because it is more easily digested when it is so heated. 



3. .To make the cream rise to the top more readily. 



4. To help keep the bottles clean. 



5 . Because it tastes better if it is warmed before you drink it. 

 Check each of the following statements which relates an adjust- 

 ment of an organism to its environment. 



1 . The cricket makes his chirping call-note by rubbing his wings 

 together. A tooth on one wing scraping across a series of ridges on 

 the other produces sound somewhat as it is made when you draw 

 your finger nail over the tooth of a comb. 



2 . The dragonfly or snake doctor is more appropriately called the 

 mosquito hawk for it captures mosquitoes and gnats and eats them 

 on the wing. So you find it usually about swamps and ponds 

 where such insects are abundant. 



3. The dandelion flower cluster closes in wet weather and 

 snuggles down to the ground but opens again when the sun shines. 



4. During the recent war nearly a quarter of our entire supply 

 of walnut trees was cut to furnish wood for aeroplane propellers and 

 rifle stocks. Walnut is strong, does not readily splinter and works 

 well under cutting tools. 



5. Woodchuck digs himself a hole and after stiiffing his baggy 

 hide until it can hold no more of fat he crawls down a few feet in it 

 through the winter to a comfortable temperature more equiable 

 than bobolink finds in his southern home reached by hundreds of 

 miles of weary travel. 



T.wo hectograph plates, which were not engravable were also used by 

 Dr. Downing. One with two boys upon a see-saw teeter with the inscription : 

 "The boys find the teeter will not work — one end stays down. Can you 

 tell how to fix it, so it will work and why?" The other a plate with out- 

 lines of leaves of elm, tulip, oak and poplar for identification. 



Editor. 



