Fungous Disi-asi^s oi- Plants, Pi-ach Yellows 155 



which was doing serious damage to the vineyards there. Before 

 he left, he advised Smith that he and Deal had strongly recom- 

 mended him for membership in the Society for the Promotion of 

 Agricultural Science. Since the start of his field studies. Smith 

 had been sending to the Department at Washington specimens of 

 fungi, especially those concerned in diseases of cultivated plants. 

 In turn, he was furnished drying paper, alcohol, twine, and other 

 accessories to preserve his materials for future laboratory examina- 

 tions. Some of his fungous collections may have been made for 

 purposes of completing his report on the distribution and severity 

 of the potato rot.' He was still working under an order to place 

 in manuscript his deductions as to the history and development of 

 this malady and the results of his laboratory " observations on the 

 growth and development of the fungi upon the tubers." During 

 the previous spring, winter, and autumn, he had used a Zentmeyer 

 microscope, and now Scribner wanted to exchange this for a 

 Zeiss instrument which Smith had with him in the field. 



Scribner did not always agree with Smith. But the chief allowed 

 his assistant freedom of choice in research. Scribner was skeptical 

 of whether Smith would find "a specific origin or cause for 

 'yellows,'" and Smith himself was not altogether convinced that 

 he would locate a parasite. He collected soil samples to study 

 peach fruit deterioration on the basis of a lack of proper nutrition. 

 Chemists of the Department were few. But Scribner promised to 

 secure, when possible, their services to analyze the soil and wood 

 samples which Smith submitted. Scribner approved Smith's plan 

 of " treating diseased trees with special fertilizers." 



That autumn the chief ordered from him the completion of his 

 report on the potato rot and a report on the progress made in his 

 peach yellows investigations. Smith protested and won the privi- 

 lege of completing his yellows research as he had planned. Scrib- 

 ner warned that funds might not allow their completion. The 

 determined young research scientist, nevertheless, began systemati- 

 cally to examine at the microscope the interior structures of healthy 

 and diseased peach twigs. Memoranda of November, 1887, indi- 

 cate that he stained cross sections of materials and examined 

 carefully their tissue and cellular structures, especially those of 

 the cambium. All this was done, presumably, to locate a parasite 

 or explain the conversion from healthy into diseased activity, 

 once the malady had taken hold. That month, when Smith was in 



