STRUCTURE AND PROPERTIES OF PROTOPLASM 69 



Stages may readily be made to order in some such form as that described 

 above (Botanical Gazette, 27, 1899, 256, and first edition of this book, 56). 

 More simply (and necessarily less accurate) they can be made from a flat 

 plate of copper having a sleeve for the thermometer, as described by E. L. 



FIG. ii. TEMPERATURE STAGE, STUDENT FORM; Xf. 



WALKER in the Journal of Applied Microscopy, 6, 1903, p. 2549. And they 

 might even be improvised from a metal plate with thermometer clamped 

 thereto, though results could be only of the crudest. 



In this, as in all such studies where the manipulation is new 

 to him, and where the individual variability of the material may 

 also play a part, the student should not trust to a single experi- 



