Bitter Pit in Apples. 379 



periods of immersal were used with the Five Crowns sorts. 

 Apart from the necessity of using pure copper-free distilled 

 water, care must be taken that the o-lass vessels used are chemi- 

 cally clean. The best method of assuring this was found to be 

 by polishing them internally (IJ litre gas cylinders) with a 

 damp cloth and precipitated chalk, and then rinsing well with 

 tap water, and finally with distilled water. This method was as 

 effective as coating the vessels internally with paraffin. A 

 litre of solution was used to each apple, since this appears to 

 be approximately eqnal to the total quantity of water used or 

 stored by a fairly large apple during its development while 

 attached to the tree. 



Mercuric Chloride. — 



Prepared Scarlet Nonpareils. — Floating on solution one week, 

 and examined after three days in air. One gram HgCl.^ per 

 200,000 c.c. water. Large, deep brown pits at each prepared 

 spot. 



One gram per 1,000,000 of water. Pits similar, but not quite 

 so deep. The Federal Analyst reported that " extremely faint 

 but distinct indications of mercury were detected in the form 

 of metallic mercury. The quantity present in each instance was 

 less than approximately 1-100, 000th part of one grain." The 

 total bulks of " diseased '" tissue were approximately 2 and 5 c.c. 

 Hence the concentration in the affected tissue lay between one in 

 30 millions and one in 75 millions, i.e., very considerably less 

 than in the solution outside. The poison has, however, to dif- 

 fuse in through very narrow points of entry, and then spreads in 

 the internal pulp in concentric hemispheres of decreasing con- 

 centration as far as the pit extends, so that at the outer mar- 

 gins the concentration will be much less than at the point of 

 €ntry. 



Prepared Jonathans. — Immersed one week. Examined after 

 one week in air. 



One per 10,000. Large spots extending deep into pulp, and 

 some confluent. 



One per 100,000. Pits smaller and each one distinct. 



One per 500,000. Deep, well developed pits to each pre- 

 pared spot. 



One per 2,500,000. Pits not so deep or broad. 



13a 



