172 Physiologie. 



selten einige Minuten. Ob diese leiciit beweglichen und ver- 

 hältnissmässig specifisch schweren Krystalle als Statolithen 

 iungiren, wozu sie jedenfalls sehr geeignet wären, lässt Verf. 

 unentschieden. K. Linsbauer (Wien). 



Walter, A. D., On the Blaze-Currents of Vegetable 

 Tissues. (Journal of Linn. Soc. London. Nov. 1, 1904.) 



The pod of Pisiim sativum submitted to the blaze-test gives 

 alter a break-shock a homodrome blaze current greater than 

 0,02 volt. This is the case for either a -|- o^ a — direction 

 of the exciting current. All land plants give an appreciable 

 ,,blaze" while marine plants examined (with the exception of 

 Chorda filiim) fail to do so. In the fungi examined a „blaze" 

 was only excited by a current sent from the dorsal to the 

 ventral surface, and not by a current in the reverse direction; 

 the blaze current was homodrome. In the hartstongue fern a 

 strong homodrome blaze is produced. This current is aboli- 

 shed by tetanization. Lemna falls to „blaze". The degree of 

 vitality seems to influence the blaze-response; the ivy-petiole 

 being sluggish gives a response less than 0,01 Volt while the 

 more active geranium gives upwards of 0,05 Volt. Experi- 

 ments with peas have shown that readings taken every half- 

 minute and continued for half-an-hour indicate no appreciable 

 fatigue. 



Vegetable tissue show strong currents of injury from a cut 

 to an intact surface. A blaze current provoked in a vegetable 

 organ during its manifestation of a current of injury is generaliy 

 opposite to it in direction whatever may have been the di- 

 rection of the exciting current, 



Adult peas give large current of injury and large blaze- 

 current. Immature peas give a small and irregulär current of 

 injury and no appreciable blaze current apparently owing to 

 the deficiency of electrolytes. The resistance is greatly reduced 

 by a Single electric shock, probably owing to the multiplication 

 of electrolytes by dissociation, and from this very fact a fallacy 

 may arise. Suppose a highly resistant young pea to be placed 

 between the electrodes so that the current of injury is in the 

 -f direction ; a considerable voltage for compensation must be 

 used to bring the reading back to zero. If a strong induction 

 shock be now sent through the pea in a — direction, the after- 

 effect, a deflection in the same direction, may be due to the 

 large compensating voltage. 



If alternating make- and break-shocks be sent through a 

 holly-leaf, the galvanometer spot goes off in the direction of 

 the break current, simulating von Fleischl's deflection, But 

 in this case it is not a physiological eifect since a boiled holly- 

 leaf or a piece of glazed note paper will give the same effect 

 perhaps ov/ing to a variable resistance smaller to the break- 

 than to the make-current. 



