36 Alfred J. Ewart : 



ever, still present in combination with the coagulated proteid, and 

 Avill give the characteristic reactions and turn brown on adding 

 alkali. 



If all the oxygen is removed, the cells can be killed by poison 

 without turning broAvn, and if the acid sap has been given time to- 

 penetrate the protoplasm completely no browning takes place on 

 admitting air nntil alkali is added. 



When slices of pulp are dropped into absolute alcohol, which 

 destroys tlie oxidase, they remain practically colourless, because- 

 the rapid penetration of the alcohol destroys the vacuolar membrane 

 and allows the alkalinity of the protoplasm to be neutralised by 

 the acid sap before the tannin has time to oxidise. Along the veins, 

 however, where there is little or no acid sap, browning may take- 

 place, although the oxidase is destroyed by the alcohol. 



When an apj^le is cut with a sharp razor the cut surface remains 

 quite pale, whereas when scraped or cut Avith a blunt knife it turns 

 rapidly brown. 



If the cub or scraped surface of the pulp is moistened with hydro- 

 chloric acid of acidity somewhat greater than that of the cell sap- 

 (0.5 to 1 per cent.), which diffuses rapidly through the ectoplasmic 

 membrane, the cut or bruised surface remains quite pale. 



The relative rates of death, of penetration of acid, and of escape- 

 of sap appear to lie factors in producing these differences, but the- 

 matter needs further investigation. 



The Anaepobiosis of the Apple. 



McAlpine (IJeport p. 42) states that when the supply of free- 

 oxygen is cut oft" apples and pears can still live for months. No- 

 experiments or references are given in support of the statement. It 

 has long been known that apples will live for a long time in a con- 

 fined space, but then they contain a large amount of air to begin 

 with, and their i-espiration is not very active, particularly at low 

 temperature's. 



Yates' Pipi)iii apples were placed in an air-tight i-eceiver, ex- 

 hausted, tilled witli puie CO.,, again exhausted, and the process 

 repeated several times daily for the first three days, and then every 

 third day. The leiiipcratui-c averaged 14— IS deg. ('.. reaching 20 

 deg. C. twice dui-ing (lie longest period of exposure. After two 

 weeks in CO, ;i,ll were sound and living, but after one week in air 

 slight decay was shown at some pgints near the surface. 



After three weeks in CO.,, the i)ulp was collapsed, and dead on 

 the surface at some points. The fact that the dead tissue was- 



