entire lives studying just one part of 

 biology do not then feel that they have 

 mastered it completely. 



The knowledge of how organisms are 

 constructed becomes especially valuable 

 when you go on to learn how organisms 

 carry on life activities. If you know 

 how vou digest and absorb food, how 

 you breathe, how your blood circulates, 

 how your actions are controlled, how 

 it happens that human beings are like 

 their parents, and how human beings 

 have developed through the ages, you 

 will have important information about 

 yourself. To understand this w^ell you 

 will need to learn something about the 

 structures of other organisms, such as 

 lower animals and even plants, and how 

 they carry on their life activities. 



Man and other living things. There 

 are even better reasons for learning how 

 other organisms carry on their life ac- 

 tivities. Consider plants; it is important 

 to you and to me that plants be raised 

 for our use. If the wheat crop is a great 

 deal smaller than usual, we may have 

 less bread; if the corn crop fails, cattle 

 and hogs are scarcer and the price of 

 meat goes up. In fact, if there were no 

 plants on this earth we would not be 

 here at all. 



Then consider the many animals such 

 as rabbits, moles, and particularly in- 

 sects, that injure crops and interfere 

 with the production of food and mak- 

 ing a living. There are also many organ- 

 isms that attack man directly, causing 

 disease. It is well to know something 

 about all these organisms and to know 

 how we can protect ourselves and our 

 crops against them. Men are constantly 

 affected by other living things. 



Biologists Study Anmials and Planus 



The work of biologists. Since the field 

 of biology is so large, the work of bi- 

 ologists is varied. Some biologists live 

 out of doors, exploring and learning 

 about plants and animals at first hand 

 by observation and recording. Some 

 biologists work in the laboratory, ex- 

 perimenting with living things or with 

 chemicals in test tubes; some study 

 plants or animals at close range through 

 the microscope to learn the secrets of 

 living matter. Before you plunge into 

 the study of living things let us see how 

 some of these biologists do their w^ork. 



Biologists explore the world. Do vou 

 know what kinds of plants and animals 

 live on this earth? Do you know w^hat 

 plants and animals live on the island 

 of Borneo or along the Amazon River? 

 Could you describe a scene in the Gobi 

 Desert of Asia or picture to yovu'self 

 the plants that make summer beautiful 

 within the Arctic Circle? 



It seems that similar questions have 

 always interested man. There have al- 

 ways been men bold and adventurous 

 enough to undertake long voyages to 

 distant parts of the earth merely to see 

 and collect the plants and animals liv- 

 ing there. 



About two hundred years ago Carolus 

 Linnaeus (lin-nee'us), a young student 

 at a Swedish university, was sent by his 

 country to Lapland to make collections 

 of living things. He started alone, carry- 

 ing in his leather bag a simple micro- 

 scope, a telescope, paper for drying 

 plants, and writing materials for taking 

 notes. For many months he endured 

 great hardships. During this time he 

 reached the Arctic Ocean on foot. Then 

 he returned to his university with a few 



