TEACHING AND LEARNING 27 



experimental study may be. This plan I have modified in some 

 cases where, as in Protoplasmic Streaming, in Photosynthesis, 

 and in Transpiration, a certain topic or experiment seems to 

 give exceptional opportunity for training in scientific ways of 

 working, or for the acquisition of knowledge particularly impor- 

 tant to the physiologist. To those problems or subjects, whether 

 to be studied experimentally or through the literature, which 

 seem to me of such fundamental importance that every student 

 should fully know and describe them, I have given additional 

 prominence by italic type, leaving matters of lesser importance 

 without such emphasis. These latter topics, including the sug- 

 gested experiments, will serve as good problems for individual 

 students. I have sought- always to make clear, by suitable 

 introduction or comment, the theory of each experiment. In 

 citing literature I have expressly avoided a duplication of any- 

 thing in the admirable works of Pfeffer and of Jost, and have 

 confined my references to such comprehensive or otherwise 

 especially excellent papers as I think it particularly advanta- 

 geous for students in this course to read. In many cases it will 

 happen that, in his elementary course, the student will already 

 have tried, or have aided in trying, some of the principal experi- 

 ments, in which case he had better not repeat them, but, review- 

 ing his earlier knowledge, he should concentrate upon matters 

 new to him. To the form of the problems and their wording 

 I have given much study, since through them the student's 

 attention may be directed in the most profitable lines, his energy 

 may be made most telling, and his attack on his topics may be 

 made inductive, while through them, also, much both of sugges- 

 tion and of stimulus may be conveyed. Since all physiological 

 processes have their seat in Protoplasm, the course begins with 

 a study of that substance; it then takes up the processes some- 

 what in the order of their dependence upon one another, Photo- 

 synthesis, most fundamental of all, coming first. But secon- 

 darily, attention is also given to the conditions of the college 

 year, for which reason Growth and Irritability come last, in 

 their proper place in the spring. The outlines embrace a full 



