68 PROCEEDINGS OF THE ACADEMY OP [Feb., 



pul vini of the inserted lateral leaflets. Bose by his experiments proved 

 that the ascent of sap is brought about, not by any localized group of 

 cells in a particular region, but by cells which extend throughout the 

 length of the plant. Even after some of these have died, therefore, 

 by the access of the poison, those above are still active, and will con- 

 tinue to exhibit suction until they in their turn are finally killed. It 

 is thus evident that the movement of ascent cannot be completely 

 abolished until the poison has reached effectively the very top. As 

 all the living cells are actively concerned in the work of suction, this 

 conveyance of poison to the top of the plant is what was to have been 

 expected. Only after such conveyance indeed could permanent arrest 

 possibly take place. Bearing these facts in mind, the action of the 

 chemicals on the various twigs used in my experiments become very 

 much simplified, and, instead of being very complex and unintelligible 

 phenomena, became reducible to one or two simple kinds of activity. 



Another important principle to be deduced from the experiments 

 of the first and also of the second year is, that the experimenter is 

 unable to disturb the natural sequence of bud opening by the stimulus 

 imparted to the twigs by the various chemical solutions. In only 

 one or two instances did the chemical seem to react upon the buds 

 and cause their enlargement out of the usual sequence. These cases 

 were with Forsythia viridissima twigs in the ammonium hydrate solu- 

 tions and in the five-drop hydrochloric acid solution. The response 

 was appreciably earlier and greater than with the twigs in filtered water 

 alone, or in the chemical solutions. The Populus monilijera twigs 

 in the ether water responded seven days in advance of the other 

 twigs placed under various experimental conditions. The results 

 obtained seem to indicate that the chemicals do not influence either 

 the time or the order of the response, but that this time and sequence 

 depend upon some factor not directly influenced by the environment 

 or by the experimental conditions. One then looks to the hereditary 

 influence which determines the time and the sequence of bud develop- 

 ment. Under hereditary influence we may include the minuter 

 structure of the plant which determines what the character of the 

 response must be. Perhaps it is a structural preparedness and the 

 character of the reserve food which determines the sequence of bud 

 development. To determine this point a study was made of the 

 microscopic anatomy of the experimental twigs. These are described 

 in the order in which the twigs responded in their bud development. 

 The twigs were cut on March 13, 1907, before the advent of Spring, 

 which occurred on March 30 and 31. 



