505 



Physiological Apparatus. 



Frank Marion Andrews. 



Introduction. 



It is frequently the ease that nuich of the apparatus required to carry 

 on work properly in Plant Physiology is so expensive that for any one 

 laboratory to possess all that is needed is quite out of the question. This 

 has led me to plan and have constructed a few very desirable pieces, 

 concerning which this paper makes mention. I am aware of the fact 

 that no lack of contrivances have been njade to illustrate some of the 

 principles here set forth. However, for simplicity of construction and 

 perfect adai>tation to the purposes for which they were intended, they will 

 certainly be found superior in many ways and useful by any one inter- 

 ested or engaged in physiological work where such apparatus would be 

 involved. It has therefore occurred to me to describe the various pieces 

 of apparatus as concisely as possible and present them, together with the 

 illustrations, in the following brief account: 



I. Heating Stage for the Microscope. 

 This piece of apparatus consists of a rectangular sheet of copper, 60 

 em. long, 8 cm. wide and 2 mm. thick. Figure 1 shows a view of the 

 lower side. It will be seen from this view that the copper does not rest 

 directly on the stage of the microscope but is held away from it a dis- 

 tance of 1 cm. This is accomplished by a strong frame of wood B, 



Fig. 1. 



7 cm. square and 8 mm. in height. Between the wood and the copper, 

 as an extra preventive against the conduction of heat in long continued 

 experiments, a layer of asbestos 2 mm. thick is intei'posed at C. The 



20— A. OF Science, '04. 



