485 



composed lialf of corn meal and half of rye meal, for nse as army rations, in place of a 

 liread made of rye exclusively. I liavi; already caused several loaves of such bread to 

 he baked, and have submitted them to various persons, amou-;- tlieni some Government 

 ofdcials, and I uuiy state that in every case where tested this bread has receiveil the 

 highest commendation. Its cost -will be much less than a bread consisting exclu- 

 sively of rye, and I am satisfied tliat high medical authorities will substantiate its 

 great value as a food. 



DIVISION OF VEGETABLE PATHOLOGY. 



Bulletin No. 1. 



Peach yellows and peach rosette, E. F. Smith (pp. G.j, plates 

 38). — The first part of this report is on investigations and exi)erinients 

 during the past .'} years with reference to the coramunieability of peach 

 yellows. The destructive nature of peach yellows and the character- 

 istics of the disease are described. An account is given of inoculation 

 experiments on a large number of trees in different localities. On 

 the theory that peach yellows is at first a local disease, experiments 

 in cutting away diseased portions of trees were made. "The results 

 varied considerably, but in no case did the removal of affected parts 

 stop the progress of the disease." Observations and experiments were 

 also made with reference to the immunity of trees from this disease 

 under certain conditions. The facts wliich the author regards as estab- 

 lished by these investigations are as follows : 



(1) The disease is contagious. 



(2) It may be conveyed by seemingly healthy buds when these are taken from dis- 

 eased trees. 



(3) Only a very small amount of infective material is necessary, provided it be in 

 the form of living cells, which can be induced to unite Avith the actively growiu"- 

 tissues of the tree. 



(4) The disease has a longer period of incubation than we have been accustomed 

 to suppose. 



(5) The death of the entire tree occurs, ordinarily, onlj^ after a very considerable 

 period, i. e. several years. 



[The hypotheses rendered probable are as follows :] 



(1) The whole tree is affected Avhen symptoms appear in any part of it. 



(2) In some cases — perhaps in many — the })eriod of incubation, i. e. the time 

 between the insertion of a diseased bud and the appearance of the disease, is longer 

 than any yet clearly established. 



(3) The disease is also communicated to budded trees in some other way than by 

 bud inoculation. This is probable in case of many young trees, and is almost cer- 

 tain in case of old trees. 



(4) The trees are not infected through the blossoms. This is inferred from the 

 result of the excisions, and from the fiict that in some cases the disease appears to 

 develop between fall and spring, and to stimulate the blossoms themselves to an 

 unnaturally early developnu-nt. 



(5) Since diseased trees have been shown to be very full of infectious matter, it 

 must be that, for unknown reasons, much of this iails to hud an immediate entrance 

 into healthy trees, otherwise the peach would soon disappear entirely. 



Three special lines of inquiry are now under consideration and will receive 

 undivided attention as soon as the laborious experiments with fertilizers have been 

 completed. These are as follows: 



