Plachd on a Nation-wide Basis 207 



worked on his report and made use of the Department's laboratory 

 facilities, he again wrote to Smith: 



'Tis Tuesday cvcninq and I am at my room. Tired as usual at ni^ht. 

 Have been hard at the subject of Dematophora etc. at the Dcp[artmen]t 

 today. Ihank goodness I am now beginning to see daylight through the 

 other side of my report. If my nerves hold out I expect to complete the 

 ms. in two to three weeks. Have to consider noti-parasilic distunes, the 

 nature of disease, and methods of treat »ient tried. I have also to write 

 the opening chapter on the " situation." Probably may have to speak of 

 the hot house experiments also though that depends on Proffessor] 

 Galloway's ideas. I have said nothing of my experiments in California 

 along that line and don't care to until the work is more complete — hope 

 Mr. Galloway will think the same about the hot-house work as its results 

 were all negative. I hope you are doing nicely in your peach orchards 

 nowdays. I would like to drop in on you. . . . Swingle appears to be a 

 good fellow and smart as you said — good addition to the strength of the 

 Division. Waite is north spraying trees. He has made some good points 

 this spring I think. . . . Has demonstrated that crabs and pears may be 

 blighted through the flower without puncture, that the other flowers on 

 the same tree will be blighted without further inoculation — probably by 

 transfer of germs by insects, has captured insects and grown germs from 

 them, has shown on a small scale that the Bordeaux mixture will kill germs 

 in inoLula!:ed l^owcrs and also prevent the blighting the same. Good strong 

 points and valuable in my estimation. 



Smith had already begun to gather literature on plant disease 

 dissemination. Pierce's letter was written on May 5, 1891, and 

 two months before, on March 5, Trclease of the Shaw School of 

 Botany had responded to a request from Smith for his published 

 writings, if any, on the subject, saying: " My lectures on dissemi- 

 nation were never published. All I had was a synopsis of topics, 

 distributed at the lectures, and no copies were saved." 



Smith believed that the "greatest advance of this decade, prob- 

 ably, was the discovery that diseases of animals and plants may 

 be disseminated by insects and arachnids. This idea," he said,"* 



did not come wholly out of the blue. Nothing ever does. Various persons 

 had ascribed Texas fever to cattle ticks. Arthur had suspected insects of 

 carrying pear blight and Carlos Findlay, of Havana, as early as 1881 had 

 suspected the mosquito of being the transmitter of yellow fever, and had 

 actually pointed out the particular one that does it {Aedes aegypti). But 

 these were happy guesses unlike a thousand others. There have been in- 

 numerable hypotheses on all sorts of subjects, some very clever ones, from 



** Fifty years of pathology, op. cit., lA-l"). 



