53 8 THE POPULAR SCIENCE MONTHLY. 



there are such things as types of form among animals and vegetables, 

 and for the purpose of getting a definite knowledge of what constitutes 

 the leading modifications of animal and plant life it is not needful 

 to examine more than a comparatively small number of animals and 

 plants. 



Let me tell you what we do in the biological laboratory in the 

 building adjacent to this. There I^ecture to a class of students daily 

 for about four and a half months, and my class have, of course, their 

 text-books ; but the essential part of the whole teaching, and that 

 which I regard as really the most important part of it, is a laboratory 

 for practical work, which is simply a room with all the materials ar- 

 ranged for ordinary dissection. We have tables properly arranged 

 in regard to light, microscopes, and dissecting-instruments, and we 

 work through the structure of a certain number of animals and plants. 

 As, for example, among the plants we take a yeast-plant, a Protococcus, 

 a common mould, a Chara, a fern, and some flowering plant ; among 

 the animals, we examine such things as an amoeba, a Vorticella, and 

 a fresh-water polyp. We dissect a star-fish, an earth-worm, a snail, 

 a squid, and a fresh-water mussel. We examine a lobster and a craw- 

 fish, and a black-beetle. We go on to a common skate, a codfish, a 

 frog, a tortoise, a pigeon, and a rabbit, and that takes us about all the 

 time we have to give. The purpose of this course is not to make 

 skilled dissectors, but to give every student a clear and definite con- 

 ception, by means of sense-images, of the characteristic structure of 

 each of the leading modifications of the animal kingdom ; and that is 

 perfectly possible, by going no further than the length of that 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 which the 

 forms I have mentioned severally belong. And it then becomes pos- 

 sible for him to read with profit, because, every time he meets with 

 the name of a structure, he has a definite image in his mind of what 

 the name means in the particular creature he is reading about, and 

 therefore the reading is not mere reading. It is not mere repetition 

 of words ; but every term employed in the description, we will say, 

 of a horse or of an elephant, will call up the image of the things he 

 had seen in the rabbit, and he is able to form a distinct conception of 

 that which he has not seen as a modification of that which he has 

 seen. 



I find this system to yield excellent results, and I have no hesita- 

 tion whatever in saying that any one who has gone through such a 

 course attentively is in a better position to form a conception of the 

 great truths of biology, especially of morphology (which is what we 

 chiefly deal with), than if he had merely read all the books on that 

 topic put together. 



