30 



fluctuation this is exposed by changes in temperature is best seen in Fischer's' 

 investigations cited by Pfefifer-. In the so-called starch trees, like the linden 

 and birch, it is found that starch is formed in the bark within a few 

 hours after the branches have been brought into a warm room from a 

 winter temperature. In the cold, sugar is again produced from this starch. 

 This conversion may be repeatedly produced and this kind of sugar forma- 

 tion seems to appear in many plants with a lowering of the temper- 

 ature. If now, for any reason whatever, the sugar formed from the 

 starch is conducted aw^ay from the organ the whole tissue may be im- 

 poverished. Pfefifer furnishes proof of this by the experiments carried 

 out in his institution by Hansteen" and Puriewitsch^. By a con- 

 tinued removal of the sugar by diosmosis, it was possible to cause an ejection 

 of starch from the isolated endosperm of grasses as well as the cotyledons 

 of Phascolus which had been cut off from the plant and a giving ofif of the 

 glucose from the separate scales of the bulbs of Allium Ccpa. If only a 

 little water was present into which the sugar could pass from the organs the 

 ejection came to a standstill because a two to three per cent, sugar solution 

 inhibits the conversion of the starch. Therefore, either a good deal of water 

 must be present or some other means for the removal of the starch if the 

 ejection should be completed. Conversely, a refilling of the organs with 

 starch could be determined if a still more concentrated solution wcm'c used. 



These examples may sufifice to show how in the plant body all the me- 

 tabolic processes and all the resulting constructive piocesses succumb under 

 constant quantitative changes which radiate in all directions from the first 

 form of attack of the factor causing the change. Each change occurring 

 locally is a disturbance in the condition of equilibrium existing up to that 

 time in the molecular organization. If the disturbance is completed in one 

 cell it must, so far as dififusible substances are concerned, be continued in the 

 neighboring ones as are all dynamic processes. 



Each place in w^hich a new structure is formed becomes a centre of 

 consumption. The supply of food to this new structure leads to a reduction 

 in other parts. Each local increase in photosj'nthesis exerts its influence on 

 the immediate surroundings not concerned in this process. The different 

 factors of growth now act uninterruptedly on the plant body and disturb the 

 momentary equilibrium, first in this direction, then in that. \\& have there- 

 fore a continued fluctuation in all life processes which is increased still more 

 by the capacity for reaction peculiar to the individual, for we dare not forget 

 that in restoring the disturbed equilibrium the organism must endeavor to 

 increase its production of dififercnt substances. If. for example, there sets 

 in an increase of the basic compounds conditioned by nutrition, an increased 

 acid content will have to be brought about and conversely. And within the 

 constant fluctuations which are a necessarv result lies the condition which 



1 Fi.scher, A.. Jahrb. f. wiss. Bot. 1891. Vol. 22. 



- Physiology I, p. 514. 



3 Hansteen, Flora, 1894. Supplement. 



* Puriewitsch, Ber. d. Deutsch. bot. Ges. 1896. p. 207. 



