PEEFACE IX 



sufficient of manipulation to warrant trusting him with 

 a microscope. His power of observation will be devel- 

 oped only by training. It is advisable to begin with 

 the lower forms, not only because of their simplicity of 

 structure, but also because of the value of this method 

 in tracing the development both morphologically and 

 physiologically of the tissues and organs of the higher 

 organisms and the evolution of forms. Though this 

 plan seems preferable, it is not absolutely necessary 

 that it should be followed. The student may begin 

 with the highest form and work downward ; or he 

 may commence with an intermediate form and work 

 either way ; again, he may begin with an intermediate 

 form, then go to the lowest and work upward. On ac- 

 count of lack of instruments, it may be necessary to 

 omit all of the minute organisms and all of the micro- 

 scopic work on the higher forms. It is thought that 

 the guide can readily be adapted to any of these meth- 

 ods. The end to be attained is not to examine as mcmy 

 specimens as possible, but to examine them as thor- 

 oughly as possible. 



It has been found that the question stimulates the 

 student to a degree of mental endeavor far beyond that 

 attained by the attempt to verify a printed statement. 

 A few of the questions are suggestive rather than capa- 

 ble of a definite answer, but these will be found to have 

 their use. The notes made in the laboratory should 

 form the basis of the recitation, and many of the top- 

 ics should be further elaborated and discussed by the 

 teacher. 



Much of the pleasure and instruction to be derived 



