ON BIOLOGY. 75 



ing facts as they are presented on the part of the vast 

 majority of insects. With a definite knowledge of that 

 much at his command, and especially a comprehension 

 of the nomenclature used in the description of the various 

 structural parts, the student will find that the transition 

 to the study of those modifications in the anatomy of 

 other insect forms is natural and not difficult, so that by 

 the study of a comparatively few more well-chosen speci- 

 mens he soon acquires a wide understanding of the whole, 

 and is capable of comprehending the most of what he 

 reads in his text-books on the subject. 



In a similar manner one may master the Jfe-histories, 

 the morphology and physiology of a number of well- 

 selected specimens or types of the lower and higher 

 forms of plant life, when it is soon ascertained that he 

 has at his command the knowledge which permits him 

 to comprehend more or less of the history, origin, devel- 

 opment and growth of the entire vegetable kingdom. 

 Thereafter, special modifications presented on the part 

 of peculiar forms of plant-life are easily understood with 

 scarcely any additional labor. Types of the vnrious 

 groups of the invertebrate* should be examined and com- 

 pared in a like method, all the way from an amoeba up to 

 a erood typical beetle. 



Passing next to the vertebrates, good representatives of 

 all the main groups shouM be examined in the same 

 way; the various structures thoroughly intercompared; 

 studied by means of diagrams; and accounts of their 

 anatomy reviewed in the best text-books on the subject, 

 Useful types for this purpose are seen in the well-known 

 lancelet; in a typical shark or ray; any teleosteon fish; 

 the frog; a turtle; any ordinary bird form, as the common 

 fowl; and, finally, some type mammal, which may be 

 met by either the common cat or the rabbit. This is the 

 plan adopted by the best biological laboratories both in 

 this country and abroad, and of its aims a prominent 

 instructor has said: "The purpose of this course is not 

 to make skilled dissectors, but to give every student a 

 clear and definite conception, by means of sense-images, 

 of the characteristic structure of each of the leading 

 modifications of the animal kingdom; and that is per- 

 fectly possible, by going no farther than the length of 

 the list of forms which I have enumerated. If a man 

 knows the structure of the animals I have mentioned he 

 has a clear and exact, however limited, apprehension of 

 the essential features of the organization of all those 

 great divisions of the animal and vegetable kingdoms to 



