March 31, 192 1 J 



NATURE 



155 



bv hydroxyl during diazotisation. Numerous cases of 

 this substitution have since been noticed and shown 

 to be capable of industrial application in the produc- 

 tion of useful mordant dyes. 



During the greater part of their joint career at 

 Finsbury, Meldola and Streatfeild had as research 

 assistants at any given time only one or two senior 

 students chosen to work for one session in the pro- 

 fessor's laboratory. Streatfeild, however, had a wonder- 

 ful faculty for dovetailing together instruction and re- 

 search, and Meldola had the happy knack of fftrnish- 

 ing his youthful collaborators with an "Arbeit " which 

 generally blossomed into a contribution to the 

 Chemical Society's Transactions within this annual 

 period of apprenticeship. From 1908 onwards the 

 council of the college provided the professor with 

 a whole-time research assistant, who generally held 

 this coveted post for about three years. The 

 senior students who were fortunate in receiving 

 this more prolonged experience in research have 

 justified their training by gaining responsible indus- 

 trial appointments within a short time of leaving 

 college. 



When the writer succeeded his former teacher in 

 iqib the work of the Finsbury laboratories was 

 dominated by the exigencies of the war, then entering 

 on its critical stages. The Trench Warfare Depart- 

 ment employed in the Finsbury laboratory of applied 

 chemistry a small works plant for smoke-bombs 

 and other munitions, which was not at that critical 

 time to be found in any other London college. In 

 19 17 the institute sanctioned an extension of the 



i chemical department, and the additional facilities 



thus provided were promptly made use of by the 



Chemical Warfare Department, which maintained a 



staff of research workers at the college until after 



t the armistice. At the same time the chemical school 



remained in touch with the synthetic colour industry, 



inasmuch as the new research laboratories afforded 



accommodation to a group of chemists sent by the 



! British Dyestuffs Corporation to extend their experi- 



i ence of organic synthesis. Other firms also took 



advantage of the research equipment for applied 



I chemistry which was now being made in the chemical 



\ workshop, and several experienced chemists were 



I allotted laboratory facilities for their researches in 



various branches of chemical technology. The 



' materials required by these research workers were 



I in certain instances prepared by senior students of 



the chemical department, who thus benefited by being 



brought at an early stage into contact with the 



actualities of industrial practice. 



With a high tradition of practical laboratory in- 

 I struction extending over a period of forty years it is 

 ; not surprising to find that the senior alumni of the 

 Finsbury chemistry department now occupy responsible 

 ( positions in every centre of chemical activity in the 

 British Empire. It is, moreover, a noteworthy con- 

 sequence of the close association of the college with 

 I the industrial life of the country that several im- 

 ; portant chemical firms are taking an active interest 

 '■ in the Finsbury defence movement, thus showing in 

 I a practical manner their appreciation of the training 

 afforded in this historic school of chemistrv. 



Bacterial Diseases of Farm Crops. 



IN certain seasons some of the bacterial diseases 

 which attack farm crops do sufficient damage to 

 become serious economic factors. An instance of this 

 was provided in 1918 by the "halo-blight" of oats 

 which caused much trouble throughout Wisconsin 

 and other parts of the United States (C. Elliott, 

 Journ. Agric. Research, 1920, vol. xix., No. 4). The 

 blight appears to be present in oat-fields every season, 

 but attracts attention only when it develops strongly 

 and does serious damage under particularly favour- 

 able weather conditions. The epidemics disappear if 

 the weather changes to a type more favourable to the 

 development of the plant. 



The halo-blight usually appears as lesions on the 

 leaves, but may occur on the leaf-sheaths and glumes ; 

 infected areas show a centre of dead tissue surrounded 

 by a halo-like margin of chlorotic tissue, and they 

 gradually spread and often coalesce until large areas 

 are involved and the whole leaf becomes dry and 

 brown. A typical white organism has been isolated 

 from these lesions, for w-hich the name Bacterium 

 coronafaciens, n.sp., is proposed. The organism is 

 a motile rod with rounded ends, sometimes occurring 

 singly or in pairs, but usually in short to long chains. 

 One to several polar flagella have been made out, 

 but no spores have been observed. The bacteria live 

 through winter on the see^, produce primary lesions on 

 the first leaves of seedlings, and are carried to other 

 leaves bv wind and rain. Natural infections of halo- 

 blight have been observed only on oats and rye, 

 though artificial inoculations indicate that the 

 organism may be slightly pathogenic on wheat and 

 barley also. Infection takes place more readily on 

 injured than on uninjured parts of the plants. In 

 normal circumstances different varieties of oats show 

 differences in susceptibility to the disease. 



NO. 2683, VOL. 107] 



Though halo-blight is known to be seed-borne, no 

 : practical method of seed treatment has yet been found 

 ' which will entirely control the disease. Treatment 

 with I in 320 formalin, as is used for smut, keeps 

 the blight in check, but is not entirely effective. 

 Heating the seed in a hot-air oven for thirty hours at 

 100° C. completely checks the disease, but the com- 

 mercial application of the treatment has not yet been 

 worked out. 

 i An unrecorded bacterial disease, basal glume -rot of 

 wheat, was discovered in 1917 by L. McCulloch 

 {Journ. Agric. Research, 1920, vol. xviii.. No. 10) 

 \ on plants obtained from various localities in Canada 

 1 and the United States. The leaf, head, and grain 

 i of wheat are all affected, the diseased portions being 

 discoloured and blackish, and the basal ends of the 

 grains often appear charred. The development of the 

 grain is hindered when the disease appears early in 

 life, but it is possible for the plants to be attacked 

 when the ears are well filled out. Bacteria are 

 abundant in all the discoloured tissues, and are fairly 

 , resistant to desiccation, as the organism has been 

 \ isolated from dry w^ heat-kernels kept at room-tem- 

 perature for seventeen months. The organism, for 

 which the name Bacterium atrofaciens is proposed, 

 is a white, polar-flagellated rod, producing a green 

 I fluorescence in the ordinary culture media. It attacks 

 starch, and will tolerate sodium chloride up to a 

 strength of 5 per cent., above which no growth occurs. 

 Many tests of the reaction of the bacteria have been 

 made, and the optimum growth-temperature appears 

 to be between 2-^° and 28° C, the thermal death-point 

 being about 48° or 49° C. Ten minutes' exposure to 

 i sunlight or fortv-four hours' freezing was also found 

 : to kill most of the bacteria. No method of controlling 

 the disease is suggested. \V. E. B. 



