12 



Biologists Study Animals and Plants 



Fig. 1 1 Dr. Alexander Flem- 

 ing in his laboratory, exam- 

 ining some mold cultures in 

 test tubes. You ivill read 

 7/iore abo2it his great con- 

 tribution to the world. He 

 discovered the drug, peni- 

 cillin, (wide world) 



Ultraviolet and electron microscopes. 

 In using the ordinary microscope we 

 use light that the eye can see. A little 

 over forty years ago it was discovered 

 that one could obtain higher magnifica- 

 tion by using ultraviolet light. Ultra- 

 violet light cannot be seen by the human 

 eye but can be photographed. By this 

 means magnifications of 4000 or even 

 higher are possible. Objects that had 

 been invisible under the best microscope 

 could now be seen. More recently an 

 electron microscope based on new prin- 

 ciples has been invented. Recent im- 

 provements have given us a microscope 

 that magnifies 20,000 times. Then by 

 enlarging the negatives a magnification 

 of about 200,000 times can be obtained! 

 In just a few years biologists have suc- 

 ceeded in photographing objects that 

 no one had ever hoped to see. You may 

 expect the newspapers and magazines to 



carry exciting accounts of new discov- 

 eries in the future as the electron micro- 

 scope is applied to living things and new 

 facts are learned about their tiniest 

 parts. 



The study of living things goes on. All 

 the world over there are biologists, both 

 men and women, as well as boys and 

 girls, who continue to study living 

 things. Their activities are as varied as 

 the activities of the living things that 

 they study. There are so many problems 

 to study — there is so much we do not 

 yet know — that biological study is end- 

 less and always fascinating. 



A glance at the newspaper will dis- 

 close the fact that discoveries are being 

 made daily. As this is written it is knowxi 

 that there are four or more kinds of 

 penicillin made by mold plants. They 

 have been used successfully to combat 

 certain types of disease germs. But we 



