1917] . HORTICULTURE. 239 



" Summer-pruned trees show a tendency to mature their wood a little later 

 in the fall and might consequently be expected to be more susceptible to winter 

 injury. They have not, however, proved more susceptible to bark splitting 

 caused by severe winter weather." 



The influence of summer pruning on hud development in the apple, J. R. Mag- 

 ness (pp. 46-77). — The investigation upon which the present paper is based 

 was conducted to determine some of the influences of certain types of summer 

 pruning on buds of the apple. It included a study of the effect of these types 

 of pruning upon developing flower buds on spurs, upon leaf buds borne on 

 spurs, and upon axillary buds on the current season's growth, whether leaf 

 or fruit. The trees included in the work were in their fourth season of growth 

 when the first summer pruning was given them. But studies were conducted 

 on seven representative varieties of apples, the buds being collected at differ- 

 ent intervals during the year, prepared, stained, and mounted for further 

 comparison. The investigation as a whole is summarized as follows : 



" The method and season of spur fruit bud differentiation and development 

 was found to be identical with that described by previous investigators. Spur 

 leaf buds developed during early summer, but little growth occurred later than 

 buds developed during early summer, but little growth occurred later than 

 July in those varieties investigated. 



"Axillary buds developed very rapidly for a time following their initial for- 

 mation, then grew slowly until about the time shoot growth ceased. Initial 

 diiferentiation of axillary fruit buds occurred about one month later than 

 in spur buds on the same trees. The main differentiation took place during 

 late August and September. Method of development of axillary fruit buds 

 seemed to be exactly like that of spur fruit buds. However, they followed spur 

 buds in point of time of differentiation, and never entirely caught up with 

 them. The difference between axillary buds in general and buds on spurs in 

 general seemed to be in degree of development rather than in method. No 

 influence of the early summer heading backs could be detected in the number 

 of fruit buds formed on established spurs. Early summer heading back tended 

 greatly to reduce the number of fruit buds formed on the one year wood. Leaf 

 buds on pruned shoots, both on the primary and secondary growth, were not 

 visibly influenced by the pruning. They appeared to function like similarly 

 located buds on unpruned shoots. This, coupled with the fact that the form 

 of the summer-pruned shoot allows many axillary buds to be left at the time 

 of the following winter pruning, accounts for the greatly increased number of 

 spurs in trees that have received regularly an early summer heading back." 



A bibliography of cited literature is appended and the study is illustrated 

 by a number of microphotogi'aphic plates. 



A statistical study of the fruit-sprir system of certain apple trees, A. F. 

 Yeager (pp. 78-92). — ^This investigation was conducted to determine what rela- 

 tion various characteristics of the spur bear to fruit production. Two series of 

 data were collected. One entire series was furnished by a single 25-year-old 

 Grimes tree. The second series was obtained for the purpose of learning some- 

 thing about the life histories of old spurs, and the spurs were obtained from 

 Grimes, Domine, and Yellow Bellflower trees, all approximately 25 years old. 

 The results secured from the data as a whole are summarized as follows: 



" As a general rule, the percentage of spurs which flowered decreased more 

 or less rapidly with age, depending on the variety. The percentage of spurs 

 bearing fruits decreased much more rapidly than the percentage blooming. On 

 the average, spurs decreased in amount of fruit to each bearing spur as they 

 became older, though the more vigorous of the older spurs produced more than 



