i 6 Jean White : 



small, so fliat the characteristic reaction to Marsh's test is 

 prevented by the large mass of organic matter. In addition 

 iiny arsenic present would be in the form of an arsenate in- 

 stead of as an arsenious compound. The former supposition is 

 strengthened by the results obtained by a further experiment, 

 in which small quantities of arsenic trioxide were added to the 

 m-aterial, and still the arsenic reaction was- not apparent, 

 though larger quantities of this salt added to the material 

 responded to the ordinary arsenic tests. A further possibility 

 is that in the presence of decomposing organic compounds the 

 .arsenic of any lead arsenate entering an apple may be slowly 

 .evolved in the form of arsenutetted hydrogen. 



Conclusion. 



The results of my observations, and of the experiments 

 performed, without one single exception so far, seem to in- 

 dicate that the complaint popularly known as bitter pit is, 

 strictly speaking, not a disease at all, but rather a symptom 

 of slow local poisoning, and that in the cases actually examined so 

 far, it appears to be due to the poisonous compounds sprayed on 

 to the surface of the fruits for the eradication of pests, more 

 especially insect pests. 



The poisonous nature of these compounds depends on their 

 relative solubilities in water, and dilute vegetable acids. 

 Theoretically a good spray would be a poison which is insoluble 

 in water, and dilute vegetable acids, but soluble in the 

 digestive juices of the alimentary apparatus of the insect, and 

 it is quite possible that future researches may discover sprays 

 possessing these desired characteristics. 



As I am anxious to have this theory proved or disproved 

 as soon as possible, I should like to suggest that fruit-growers 

 in the different States should test it' in their own orchards. 

 A good plan would be to leave one central tree unsprayed, and 

 also those forming a kind of circle round it. In this m^anner 

 the danger of spray material being dejDosited upon the surface 

 of the fruit on the central tree would be minimised, in an 

 orchard which was othenvise sprayed. 



