2 INTRODUCTION 



races of men), and Ethnology (dealing with manners, customs, 

 language and other activities of the races of men). 



3. Biology deals with objects, that is, with the concrete, 

 but its chief interest and value lies not in mere description or 

 enumeration so much as in the generalizations, which may be 

 made from accumulated facts. A single observation, or 

 repeated observation of a single individual seldom justifies a 

 general conclusion, but by the comparison of numerous examples 

 one is enabled to distinguish the accidental and trivial from the 

 general and significant. Therefore, the method of study by 

 comparison is for the biologist of special importance. 



(For the individual, and especially for the average college 

 student who devotes a comparatively short time to the subject, 

 the study of many individual examples is impossible and, there- 

 fore, in practice, an abridgement of the method of study by 

 comparison is adopted. This is called the method of study by 

 types, by which a series of examples are compared, each example 

 being representative or typical of a considerable group. That 

 the examples selected are typical, rests, of course, on the 

 observation of previous students or investigators. By this 

 method the student may in a comparatively brief time extend 

 his studies over a large field.) 



4. It is usually not difficult to distinguish a living thing from 

 one not living, but to state formally what are the attributes 

 of the living is not so simple a matter. On close analysis 

 living things are found to be complex in structure, being 

 composed of many parts, called organs, which differ in struc- 

 ture and in function. For this reason a living thing is called 

 an organism, and is said to be organized. 



5. Crystals are more like organisms than any other non- 

 living thing, and a comparison of organisms and crystals will 

 serve to indicate the most essential characteristics of living 

 things. 



6. One of the most prominent characteristics of objects that 



