86 



Dr. A. D. Waller. An Attempt to Estimate 



make the electrical test upon an entire seed with unknown local bruises 

 received during its fresh state or in course of preparation, than upon a 

 previously protected portion of the seed with an obvious injured end, 

 as in the case of the radicle freshly exposed by separation of the cotyle- 

 dons, and nipped off at its base immediately* before an observation is 

 made. Moreover, in the former case the current-density is smaller, 

 the blaze effects are relatively less considerable, and the polarisation 

 counter-effects relatively more considerable. And, finally, irregularities 

 due to irregular distribution of water f are more liable to occur in the 

 comparatively large mass of an entire seed than in the comparatively 

 small mass of its removed radicle. 



Table I. — Comparison between Eadicles of Bean Embryos of the years 

 1860 and 1899. In each case the seeds were soaked in water at 

 room temperature (15° to 18°) for 24 hours before experiment. 



N.B. — In these and all subsequent experiments the radicles "were disposed as 

 described in the text, with uninjnred apex to electrode A and fractured base to 

 electrode B (fig. 1). Excitation is by a single break induction shock of a Berne 

 coil, fed by two Leclanche cells, 10,000 units, negative direction from A to B. 

 The blaze current is in the same (negative) direction, i.e., is unequivocal. 



The galvanometer was. shunted to such an extent that xijoth- volt gave a deflec- 

 tion of 4 cm. of scale. At this degree of sensitiveness polarisation currents are 

 practically illegible. 



Seed. 



1860. 



Seed. 



1899. 



No. 1 



oooooooooo 



No. 11 



-0-0750 

 -0-0400 

 -0-0700 

 -0-0600 

 -0-0350 

 -0-0350 



-o-oioo 



-0 0175 

 -0 0200 

 -0 0075 



„ 2 



„ 12 



„ 3 



„ 13 



» 4 



n 14 



„ $ 



n 15 



„ 6 



» 16 



„ 7 



* 17 



» 8 



„ 18 



„ 9 



» 19 



„io 



„ 20 







Average blaze. . 

 Grermination . . 







per cent. 





-0-03700 

 100 per cent. 



* Or some hours previously {vide note on p. 84), although in such case the 

 radicle has appeared to be more rapidly exhausted by repeated stimulation. 



f Beans soaked unequally (at the end of twenty-four hours) give blaze currents 

 from more soaked to less soaked portions and not vice versa. A bean that is left 

 for several days in water becomes water-logged and finally decomposes. Such a 

 t: drowned " bean will not germinate nor give any blaze whatever. A half- 

 drowned bean gives blaze only towards the drowned (or more soaked) half. 



