48 Proceedings of Indiana Academij of Science 



resuscitated by Sachs (1, Bd. I, p. 412). Many such examples in physi- 

 ology could be mentioned. The forgotten work of Mendal was resus- 

 citated by de Vries, Correns and Tschermak almost simultaneously (48, 

 p. 504) and also the restoration of the now famous work of Conrad 

 Sprengel by C. Darwin. 



Then there is the physical question of the Brownian movement, 

 long known and of interest to all scientists. The chemist also looks 

 for forms of energy in the atom by a rearrangement of the protons 

 and electrons and the energy of radioactive substances (64). The 

 determination of Hydrogen Ions much referred to, especially of late, 

 presents many questions which the botanist would do well to work in 

 conjunction with the chemist. The sensitiveness of the bacteria method, 

 above referred to, exceeds that of various chemical methods ordinarily 

 employed (65) and hence its extreme usefulness to the physiologist. 



The chemistry of plant odors presents many problems. Many plants, 

 such as Agerutum mexicanum, have no special odor during life but 

 when killed by drying, freezing, or heating to 60° C, they give off a 

 very pleasant odor of cumarin (33, p. 274). Similar odors appear in 

 Aspenila odorata, Antlioxantlinm odoratum, Pninus ceratius and vanilla 

 plants and the well known instances of hay and other plant odors. We 

 can smell .000002 milligram of oil of roses and .000000002 milligram of 

 mercaptan (66, p. 97). The topic of transpiration presents many 

 problems. Hales (67) proved that the flow of water may be rever.sed 

 in a stem and Stiasburger verified this by cutting off a tree trunk near 

 the base and which was naturally grafted about one meter above the 

 cut. The cut-off stem remained fresh for years (68). A summarization 

 of transpiration and the literature is given by Burgerstein (69) up to 

 1920. 



There remain questions about carbohydrates and fats. In some 

 plants no starch is formed in the chloroplast (52, p. 223) and in others 

 cane sugar formation precedes that of starch. Questions arise concern- 

 ing the absence of some polysaccharides in certain plants and some 

 doubt still exists on the functions of mono-di- and poly-saccharides (1, 

 Bd. 1, p. 468). 



Carbon is necessary for the metabolism of plants and as Noll says, 

 no other element can enter into the formation of so many and such a 

 diversity of substances in the organism or in the chemical laboratory 

 (70). A reference to the works of Richter and Beilstein will substan- 

 tiate this fact. According to Chamberlain (71) the number of carbon 

 compounds now exceeds 200,000. 



The well known process of abscission or leaf-fall can be brought 

 about in various ways. Further research is needed to determine whether 

 the production of organic acids is actually operative at the end of the 

 summer according to Wiesner's view or if organic acids may have any 

 influence (1, Bd. II, p. 278). In this connection it is interesting to 

 recall the work of E. Hannig on the casting off of flowers as a result 

 of external conditions and the field for investigation brought to light 

 by his experiments. Several points concerning the action of poison by 

 increasing the temperature as well as the differences in the resistance 



