AITEX DICKS. 





1 



130 



became elevated, and elevation of the injured pinnule was often delayed until visible exudation bed 

 appeared on the cut sarface. In the case of heavily-loaded leaves depression of the 



pet 



usually occurred, the movement immediately succeeding elevation of the injured pinnule, or of it ,u[ 



its fellow. 



Experiment III. -July 20th. Temperature 80-5° *, atmospheric humidity 95 per cent. Heavy 



rot ih 



falling at the period of experiment. Everything WH drenched tcith 

 moisture.— Amputation of the tips of terminal pinnules of leaves which were not loaded with adhere 

 drops of rain was followed only by imperfect elevation of a few distal pinnules in the injured pinna 

 No action whatever occurred even in the injured pinnule until after 

 exudation appeared on the cut surface. 



Experiment IV.— July 25th. Temperature 78° F., atmospheric humidity 94 per cent. Very heart, 



drops 



rainfall had occurred shortly btfi 

 moisture. The leaves ivere 



>f 



clouds. Everything was drenched with 



drops of ram.— Amputation of the tips of terminal pinnules was followed merely by slow and imperfect 

 action in a few of the distill pairs of pinnules in the injured pinna, save in the case of heavily btded 

 leaves, in which deep depressiju of the primary petiole occurred simultaneously with or immediately 

 after elevation of the injured pinnule. 



Expkriment V.— August 7th. The day was one of drenching, tropical .showers alternating with 

 intervals of brilliant sunshine. The leaves were in maximal diurnal position and in some instance* heavily 

 loaded with adherent drops of rain. — Amputation of the tips of terminal pinnules was followed merely 

 by very slow and. imperfect action in eight or nine neighbouring pair*, and, in the case of one 

 heavily-loaded leaf, by deep depression of the primary petiole ere any but the injured pinnule 

 had become elevated. Here all the conditions for excessive turgidity of the tissues were certainly 

 present, for there had been abundant solar stimulation in coincidence with excessive root-Mipply 

 and minimal transpiratory loss, and yet " irritability " in place of being maximal, as llaberlandt says 

 it ought to be under such circumstances, was minimal. 



Experiment VI. — September 13th. Almost uninterrupted rainfall had taken place during the %r 

 previous days and drenching showers had fallen earlier in the morning. The shy was bright, but the sun was vtited 

 by cloud. Everything was drenched with moisture. The leaves tare in mauitml diurnal position and in 

 many cases loaded with adherent drops of rain. — Amputation of the tips of terminal pinnules was followed 

 by a pause, during which no movements occurred, but drops of exudation appeared at the divided 

 extremities of the mid-rib and larger veins of the injured pinnule. Slow elevation of the injured 

 pinnule then took place. This was succeeded by a pause, after which the uninjured terminal pinnule 

 acted. Another pause ensued, followed by slow movements of elevation in a certain number of 

 pinnules in the outer half or third of the injured jinna. In the case of heavily -loaded leave* 

 depression of the primary petiole often occurred as the first sequence to elevation of the injured pinnule 

 and its fellow, and in one case as the very first phenomenon of movement subsequent to exudation on 



the cut surface of the injured pinnule. 



Experiment VII.— October 7th. Very heavy rainfall had occurred in the course of the precious night 

 and during the earlier part of the day. The leaves were in maximal diurnal position.— Amputation of the 

 tips of terminal pinnules was followed by very slow elevation of the pinnules of the injured pinna, the 

 movements being in many eases confined to the terminal third or half of its course. The primary 

 petiole in some cases became depressed immediately after elevation of the injured pinnule and its fellow. 



2. Effects following the amputation of the tips of 



VIII.~June 24th, 8 a.m. F. 



ft 



soil and air tvere very humid.- Am V utaiion of the tips of axes was attended by no results, save the local 

 exudation of a large drop of fluid on the divided surface. 



Experiment IX.-July 15th, 8 a.m. Air very moist and ground saturated owing to heny ram <n 

 the previous day.- Amputation of the tips of axes was followed merely by the exudat.on of a targe 



drop of fluid 



