632 THE POPULAR SCIENCE MONTHLY. 



training after that period is one adapted, if not intended to repress 

 the forms of observation, and hence the first thing to be taught a stu- 

 dent on entering the biological laboratory in one of the institutions of 

 the better class is how to observe. This, though it appears an easy 

 task, is really one of considerable difficulty. First, there is a tendency 

 to consult books so as to learn what is or should be seen ; and, sec- 

 ondly, there is a sudden jumping at conclusions from the most super- 

 ficial examination of the specimen, and these conclusions are adhered 

 to most tenaciously, utterly preventing the formation of any different 

 view. 



Together with the formation of habits of observation, it is desirable 

 that a certain amount of facts be obtained, and so the student is set at 

 the dissection of a selected series of animal types ; for instance, the 

 sea-anemone, sea-urchin, earth-worm, lobster, clam, and frog. Economy 

 of material is insisted upon, and the admonition is frequently given 

 that each stroke of the scalpel should mean something. Drawing is 

 extremely essential, for, if the student be made to draw exactly what 

 he sees, he will have to look more closely, and, at the same time, the 

 instructor can readily see exactly how well his pupil works, and exactly 

 where his difficulties lie. At first the student declares he can not draw, 

 that he has not the slightest taste for art, and yet, after a very little 

 experience, he makes thoroughly intelligible, if not artistic, representa- 

 tions of what he sees. 



A very important point in making these small dissections is making 

 them under water. If one attempt to dissect a clam in the open air, 

 the various parts will settle down and adhere to each other ; while, if 

 the operation be performed under water, this difficulty will be avoided, 

 the parts being buoyed up by the surrounding medium. To trace the 

 course of the blood-vessels, injections are resorted to. Some quickly 

 hardening mass, like plaster-of -Paris or melted wax, or gelatine colored 

 by carmine, vermilion, or Prussian blue, is forced into the arteries or 

 veins, and then the student, by following the streaks of color, can 

 readily follow the course of the circulation. When sufficient skill is 

 obtained by dissection of these larger forms, smaller ones may be taken, 

 and after a short time the student experiences but little more difficulty 

 in dissecting a grasshopper or a snail than in a pigeon or turtle. 



Besides obtaining a skill in dissection and a capacity for observa- 

 tion, a student is led in this anatomical course to make comparisons 

 between the various objects dissected. This results in a recognition 

 of similarities and differences, and exercises the reasoning faculties. 

 The value of the mathematical sciences in logical training is often in- 

 sisted upon, but to the writer it seems as if the biological sciences 

 were even more important from this standpoint. In mathematics, 

 given such and such premises, there can be but one conclusion ; there 

 is no alternative, while in zoological reasoning there is an element of 

 uncertainty to be eliminated. Each fact observed must be weighed, 



