xiv Introduction. 



true of such delicate tissues as that of the liver. The blowpipe 

 should be used to inflate thin-walled tubes and cavities. It is 

 also useful as a probe. A piece of copper wire, or an aluminum 

 hairpin straightened out and tipped with sealing wax, serves 

 well as a probe. For tracing very slender ducts use a bristle 

 tipped with a very small drop of sealing wax. When dissecting 

 specimens under water do not lift the specimen out to see any- 

 thing. The soft tissues sink down together in a mass that pre- 

 vents seeing as well as before, whereas while under water they 

 are partly floated up and thus made more distinct. It may be 

 necessary, however, occasionally to lift the specimen from the 

 water to make a cut near the ends, or to make some new adjust- 

 ment, as inflating through the mouth. Always follow directions 

 closely when dissecting. By not doing so you are likely to 

 waste both time and material. Read the whole sentence before 

 making a new cut. It is a good ru!3 not to cut anything unless 

 you know what it is. Keep your thinker just ahead of your 

 cutter. If in doubt, ask help of your teacher. 



General Suggestions. Arrange your table, and your position, 

 so as to get enough, but not too much, light. If two work to- 

 gether, be careful not to let the heads or hands shut out needed 

 light. At the beginning of the term learn the rules regulating 

 the laboratory, and carefully observe them. But whatever the 

 rules, be sure and keep your own table neat and clean. If other 

 students use the same table, put away all your belongings. If 

 you have the exclusive use of it, keep books, instruments, etc., 

 in order. Take pride in making your notes and drawings the 

 best possible. The book is yours to keep, and, if well done, 

 will likely be useful to you later. It is a worthy ambition to 

 desire to excel. In all your work, think about what you are 

 doing. Do not let yourself drift along thoughtlessly. No work 

 succeeds without live interest in it, ahd thoughtful attention. 

 Try to think out the use of each part or organ, the ways 

 which the animal is adapted to its place of living and to all it 

 surroundings. This 'habit of thinking about the things you 



