278 Frederick Stoward : 



.Since the behaviour of the unpeeled differs so distinctly from 

 that of the peeled tuber, in regard to the entry of salt into 

 its tissues, it is difficult to avoid the conclusion that the intact 

 skin presents a barrier to the ready entry of the dissolved sub- 

 stance. As it is difficult to devise any satisfactory colorimetric 

 method for demonstrating the presence of the small quantities 

 of the chloride in the tissue, and of thus localising its points 

 of entry, the further discussion of this aspect of the question 

 may well be deferred until certain crucial experiments with 

 tubers steeped in sulphuric acid are described and considered. 



The brines in these experiments remained perfectly clear, 

 iind slight bacterial development only took place, demonstrat- 

 ing that practically little, if any, nutrient substances were ex- 

 tracted from the steeped objects. 



Storage and cooking tests were most unsatisfactory. The 

 stored tubers rapidly softened, lost weight, discoloured and 

 finally decayed. 



Specimens from each of the series were planted in good 

 garden soil, and there remained for eight weeks. In every 

 instance the results were negative, conclusively showing that 

 the vitality of the dormant buds of the treated had been 

 •destroyed by the treatment. 



Specimens of these brine-steeped peeled and unpeeled tubers, 

 immediately after treatment, were cut in halves, and the cut 

 surfaces freely exposed to the air. After 24 hours' exposure, 

 the superficial tissue to a depth of several millimetres invariably 

 ^icquired a greyish-black to black colour. 



That this phenomenon is enzymatic in its nature is shown 

 to be highly probable by the following experiments and obsen'-a- 

 tions. 



Untreated tubers (A) and brine-steeped tubers (B) were 

 bisected and exposed for 24 hours. Both series exhibited the 

 progressive darkening of their exposed sectioned surfaces. After 

 an hour's exposure a pinkish coloration commenced at the 

 margin, later a liver-coloured tint, and still later a greyish 

 black, and finally after the lapse of 24 hours a black colora- 

 tion, the intensity and rapidity of the changes being more 

 marked in series B. 



