V 111 PEEFAOE 



ble that they should be studied in this order. Experi- 

 ence has shown that this method can be pursued with lit- 

 tle or no difficulty and to the greatest advantage. It is 

 very frequently the case, as here, that the simplest form 

 is not necessarily the best known. Every one is more 

 familiar — by sight, at least — with the frog than with 

 the amoeba. The structure of the former resembles that 

 of the human body far more than does that of the lat- 

 ter. But how many students have even the most gen- 

 eral knowledge of human anatomy? They know, to be 

 sure, that the body contains a heart, lungs, stomach, 

 etc., but in the great majority of cases would fail to 

 locate or, if shown them, even to recognize these or- 

 gans. Again, how many students, if called upon to do 

 so, could tell more about the frog than that it usually 

 lives in the water, is greenish in color, has four legs, a 

 mouth, etc., and can jump and swim ? Whether or not 

 the frog has a tail is usually a question for discussion. 

 As a matter of fact, beginning students have no more 

 real knowledge of the higher than of the lower forms. 



That the student is unaccustomed to the use of the 

 microscope is often urged as a reason against beginning 

 with minute organisms. Does his study of the gross 

 anatomy of a rabbit or of a frog teach him anything 

 about the manipulation of this instrument ? Sooner or 

 later he will have to learn to use it, and it matters little 

 when he does so ; the instrument will be unf amihar to 

 him until he actually handles it and learns its use by 

 degrees. He should approach it by way of the magni- 

 fying glass, and use the low before attempting the high 

 powers. In two hours the average student can learn 



