64 



SCIENCE 



[N. S. Vol. LII. No. 1333 



not impair the visibility of tlie mycelium. 

 In completed preparations the myceliimi, 

 spores, amoebae or bacteroidal tissues are a 

 brilliant red and host tissues green. This 

 combination gives clear differentiation for 

 visual microscopic study but for photomicrog- 

 raphy the use of filters is necessary. 



If sections are somewhat resistant to stain- 

 ing good results are obtained by first mor- 

 daunting them in a 1 per cent, solution of 

 potassium permanganate in water for 2 to 5 

 minutes, afterwards washing in water and 

 passing through graded alcohols to 85 per 

 cent. The mordant must be freshly prepared 

 as it will not keep. 



Excellent preparations have been obtained 

 with the following phytopathological material : 

 Plasmodiophora hrassicce, legume tubercles. 

 Albugo Candida, Phytophthora infesians, 

 Plasmopara viticola, Exoascus pruni, Myco- 

 sphaerella rubina, Venturia inaequalis, Cro- 

 nartium ribicola, Peridermium ialsameum, 

 Uromyces caryophyllinus, Puccinia nialva- 

 cearum, Puccinia antirrhini, Puccinia gra- 

 minis, etc. 



It is hoped that others may find the 

 method of some value. 



B. T. Dickson 



Macdonald College, 

 Quebec, Canada 



THE AMERICAN ASSOCIATION FOR 



THE ADVANCEMENT OF SCIENCE 



SECTION O— AGRICULTURE 



The sessions of Section O, held in the Soldan 

 High School, St. Louis, Mo., December 29 and 

 30th, 1919, were devoted to the discussion of the 

 geneiral subject: "The Relation of the Use of 

 Power and Labor-saving Machinery to Agricul- 

 tural Progress." For the sake of effective presen- 

 tation, the general subject was considered in. four 

 of its important relations, namely, the influence 

 of farm machinery on production, labor and 

 wages; the influence of power and machinery on 

 social and physical conditions surrounding farm 

 life; the application of power to save labor; and 

 future needs and developments. 



In discussing the first of these topics, Mr. Arnold 

 P. Terkes, of the International Harvester Com- 

 pany, referred to the evolution of farm machinery 



and pointed out that the first real farm machine 

 was invented less than half a century ago. Such 

 farm tools and implements as were used a hun- 

 dred years ago were of the one-piece variety and 

 could not be properly designated as machines. 

 They were very nearly identical with those that 

 had been used by farmers for two or three thou- 

 sand years. The invention of the reaper, in itself 

 a rather simple machine, was quickly followed by 

 other inventions represented by at least 100 dis- 

 tinct implements used on American farms at the 

 present time. "During this period of invention 

 and development of farm machines, American 

 Agriculture has undergone a tremendous change. 

 The old farming methods, which involved a great 

 deal of hand labor, have given way for the most 

 part to the use of machinery. An entirely new 

 era of agriculture has been brought about and the 

 new order has been made possible only through the 

 invention of machines which reduced the amount 

 of latior and the percentage of the population re- 

 quired to produce foodstuffs, thus enabling trans- 

 portation and other industries to develop simul- 

 taneously with agriculture." 



The invention and use of farm machinery has 

 had at least two effects on labor. There has been 

 a saving of labor by the increase in the efficiency 

 of the individual and the consequent reduction in 

 the number of men required to accomplish a given 

 task. There has been, further, a substitution of 

 animal and mechanical energy for human energy 

 and the making of farm work less irksome and ex- 

 hausting. For these reasons the employer of farm 

 labor lays less stress than formerly on mere phys- 

 ical development and is willing to pay more for 

 technical skill, initiative and manual expertness. 

 "Incidentally these changes, brought about by the 

 use of machinery, have resulted in a decided change 

 in the type of farm hands upon American farms 

 as wlhole. A few years ago immigrants who had 

 had experience on the small farms in Europe made 

 what were considered first-class farm hands, since 

 they had a fair knowledge of a type of farming 

 which did not differ materially from that found in 

 this country. At that time many of the immi- 

 grants sought employment on farms in America 

 and found it. But with the increased use of farm 

 machinery this class of labor .became less and less 

 satisfactory because very few of the immigrants 

 had any knowledge whatever of farm machinery, 

 and, as many of them could not understand the 

 English language, it was difficult to teach them. 

 The practise of hiring these "green" immigrants 

 therefore became less common. ' ' 



