38 Proceedings of Indiana Academy of Science 



can be further studied with profit. It is often quite worth while to 

 record one's failures as well as one's successes in an investigation. This 

 is frequently valuable for guidance in further research. 



Often what at first seemed to be of chief importance in a problem 

 turns out to be of minor value in comparison with later developments. 

 New points of view or new problems present themselves as he pro- 

 gresses with his problem and crowd upon his attention to such an extent 

 that a limitless field for investigation sooner or later presents itself 

 for solution. The writer realizes that work of enormous value has 

 already been accomplished and that greater discoveries are in store 

 for the future. With this view in mind he now ventures to mention 

 a few at lea.st of the problems in plant physiology for further study. 



If we direct our attention to the root system of plants we find that 

 this subject has by no means received the attention which its impor- 

 tance deserves, notwithstanding the large amount of study that its 

 various phases have received. As a root grows older it gradually 

 loses its ability to absorb water, which function is constantly relegated 

 to the young roots. The rapidity, however, that marks this change 

 and the specific modifications that occur both in cell walls and proto- 

 plasts are worthy of study. The well known cases of root contraction 

 include a number of interesting lines of investigation. Since neither 

 osmotic pressure nor the activity of secondary growth causes variation 

 in root contraction in different plants, the question of the character of 

 the active cells both as to elasticity and also localized transformation 

 requires close attention (1, Bd. II p. 17). 



A root of Faba will exert a pressure of from 300 to 400 grams and 

 will grow in clay, where it meets a resistance of 100 to 120 grams, 

 almost as rapidly as in water (2). The writer has recently found that 

 root growth of seedlings is not stopped by a water pressure of 600 at- 

 mo&pheies and that, although the root is rendered transpai-ent in a frac- 

 tion of a minute, it recovers in a few days when replanted. 



The statolith theory, ingenious as it is, requires confirmation not- 

 withstanding the galaxy of able investigators who have made contribu- 

 tions in its behalf. Various attempts have been made to explain 

 geotropism by chemical change, and this has created a field of special 

 iutcrest. Nemec found that the geotropic stimulus caused certain 

 changes in the protoplasm. Long ago Kraus (3) showed that the amount 

 of sugar increased on the lower side of a horizontal stem while the 

 acidity decreased and that later both sugar and acid decreased. Kraus 

 (4) also states that the percentage of sugar is increased in active shoots 

 that are continually shaken but this has been questioned. Czapek (.5) 

 opened up a field for investigation on the chemical side by proving the 

 formation of homogentisinic acid by the oxidation of tyrosin that were 

 geotropically stimulated. 



The character of the soil is an object of more thorough study, par- 

 ticularly with regard to the needs of certain plants whose roots often 

 undergo extensive development. Nobbe (6) has shown that the roots 

 of a wheat plant will total a length of 500-600 meters, while the roots 

 of a squash plant may attain 25 kilometers or 15% miles. It may be 



