316 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



scientific and economic interest, about which there is much to 

 learn. 



We do not know exactly how water and salts are taken from 

 the soil, how they pass upward, or whether transpiration is use- 

 ful or detrimental to the plant. Still less do we know about cell 

 physiology, with reference to protoplasm as a whole, or with 

 respect to its constituent parts. Whether there is cytoplasmic 

 continuity through plasma membranes and through perforations 

 in cell walls, or only continuity of solutions in protoplasm is 

 not decided. 



Plant respiration and photosynthesis are still confused in the 

 popular mind, nor does the botanist thoroughly understand 

 either. Whether the katabolism incident to respiration is effected 

 through analysis of protoplasm or of foods is not known. Po- 

 tential energy may be transformed into active energy through 

 respiration, but we understand completely neither the function 

 of respiration nor the process. It w-as formerly supposed that 

 plant respiration was a slow process, connected with little general 

 activity of the organism; but recent experiments indicate that it 

 may be as active in plants as in animals. Fermentation is an- 

 other physiological problem of great importance, which mainly 

 remains to be solved. 



The relation between host and parasite is a problem con- 

 cerning which there is little fvindamental knowledge. Whether 

 the parasite penetrates the ])lasma membrane and comes into 

 contact with protoplasm, and whether it really obtains organic 

 food or merely absorbs undigested materials, which it builds 

 up into food for itself are problems closely related to unsettled 

 views regarding intracellular food relations in general. It is 

 also reasonable to suppose that fungi and bacteria which we 

 suppose to be parasitic may, if they use ready-made foods, kill 

 the organic material, through enzymatic action, before appro- 

 priating it. If they build their foods from crude material, their 

 nutritional processes must be more nearly like those of green 

 plants than we have supposed. If they kill organic food before 

 using it, they would seem to be saprophytes rather than parasites. 

 Irritability and tropisms present a field of vast importance, 



