It has not been possible to carry these investigations as far as might 

 have been done. This is owing to the great distance of suitable orchards 

 for conducting the experiments from my headquarters, and it is chiefly 

 on this account and pressure of other work that compels me to abandon 

 a further prosecution of this subject under existing circumstances ; for 

 when it is stated that the majority of the experiments and observations 

 have been carried out at a distance close on a thousand miles from the 

 laboratory, some of the difficulties involved will be fully realised. 



Before I proceed to an account of the trouble, it will be well to briefly 

 refer to the more important Hterature abeady published on this subject 

 from other parts of the world, and to note the observations and conclusions 

 there arrived at. 



Literature. 



In 1891 Jones (1) described the general appearance of the disease, 

 but on the authority of J. B. ElUs put it down to the fungus Dothidea 

 pomigena, Schw. Jones says that it is quite common upon Baldwin apples 

 throughout the Vermont State, but that its occurrence upon other varieties 

 was not noticed. 



Cohb (2) a year later describes the disease, which he says causes con- 

 siderable loss. He was at first incUned to beUeve that it was due to the 

 insect Dindymus versicolor, but, after a careful examination, was unable 

 to trace any insect puncture, and concludes that the cause is unknown. 



Wortmann (3) in 1892 reports the trouble in Europe, and names a 

 number of varieties of apples on which the spot occurs. Large sappy 

 varieties are especially liable to spot, according to Wortmann. He con- 

 cludes that the death of the cells is due to a concentration of sap following 

 loss of water by direct transpiration in the case of tli? ouperficial cells, or 

 by excessive conduction of water to the transpiring surface layers in the 

 case of the deeper seated cells. 



Lamson (4) in 1897 9,&ys, that the Baldwin apple in Southern New 

 Hampshire has been badly affected with the spot for the last three years, 

 and thinks that it is of fungous origin. He conducted experiments during 

 the seasons of 1895 and 1896 on Baldwin apples with '" Bordeaux mixture" 

 and from the experiments of both seasons it is quite evident that the 

 spraying was advantageous. 



- Zschohke (5) in 1897 confirmed and extended the work of Wortmann. 

 He paid particular attention to the epidermis and its relation to the keeping 

 quaUties of the fruit. Zschokke considered that the relative rate of water 

 conduction was the most important factor in determining the suscepti- 

 bility of apples to the spot disease. 



Jones and Orton (6) in 1897 mention that although the spot trouble 

 was worse in Baldwins, it is also common in Northern Spies and Greenings. 

 They remark that the spots were more niunerous at the apical end, and 

 that they were not confined to the surface, but in some cases were deeply 

 seated. They note that the spots were associated with the vascular 

 bundles, and occurred at or near the veins. They advance no suggestion 

 as to the cause of the disease, but simply say that they failed to associate 

 fungi or bacteria with the spots. 



