18 



Alfred J. Eivart : 



YATES PIPPIN AND SULPHUKIC ACID. 

 Medium. 



Exposure and 

 Temperature 



'A days at 



0°C-1°C 



3 days at 



io°c-irc 



3 days at 

 29°C-30°C 



Water. 



Superficial brown- 

 ing to pits 1-3 

 mm. diameter, 

 and 1-2 mm. 

 deep 



Pits 2-5 mm. dia- 

 meter and 2-3 

 mm. deep 



Pits partly con- 

 fluent and 5-10 

 mm. deep 



ASfar. 



Superficial brown- 

 ing to pits 1-2 

 mm. diameter 

 and depth 



Pits 1-3 mm. dia- 

 meter and 1-2 

 mm. deep 



Pits partly con- 

 fluent and 5-8 

 mm. deep 



Total liulk of Kates ot diffus- 

 jioisoried tissue ion of H;; SOi 



0.002 C.c. - 1 at (t I'. 



O.(J03 c.c. - 1.53 ;it lOT. 



11.25 c.c. - 3.H:{at2;rO. 



Hence it follows that in still water the poison reaches the prepared 

 areas mainly by diffusion, and hence the poisonous action is only 

 slightly decreased Avhen the acid reaches the apple by diffusion alone 

 through agar. In three days only a small portion of the acid 

 present could reach the prepared areas l)y diffusion, so that the 

 sensitivity of the pulp cells to sulphuric acid is fairly pronounced. 

 Furthermore, the comparison between the rates of dift'usion and 

 the bulk of poisoned tissue at different temperatuies, sliows cieaily 

 tliat the inci-eased poisonous action at the higher temperatures is 

 not merely a matter of diffusion, but is mainly ilue to tlie inlierent 

 sensitivity to poison being greater at the highei- trmperatuiL'. 



The same is shown by the following test, in whith thiee experi- 

 ments were started at three preliminary temperatures (niii;' in all). 

 and of each set of three, one was subsequently kept in ;iir t'oi- four 

 days at — 1 deg. C, one at 10 — 11 deg. ('., and one at .id dcir. ('. 

 During the preliminary immersal for Www days. \\\v apples wfie 

 all in a 1 per million solution of mercuric chloridi.', so that tlie pie- 

 pared spots in each set of three received tlie saiii- amount of |»oisoii 

 by diffusion, but during the subsequent exposures in air a i-on- 

 sistently greater poisonous action was I'xeiHiscd at tlie liigher tem- 

 peratures. 



YATES PIPPIN IN 1 PEK MILLION HgCl^ 

 'rreat.mentf' Snbse(|uei.t treatment for 4 .lavs in air. 



Immersed for: OoC-Ioq. liioc.-uoc. 



3daysat C'C'-lT. - Superficial brown- - Distinct but super- 

 Froni very faint ing only ficial browning 



.superf i ci al on each ])repare(l 



browning to no spot 



signs of poison- 

 ing 



;{oot;. 

 Pit.s 1-2 mm. diam- 

 eter superficial 

 to 1 mm. deep. 



