. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. now TO AVOID CONTAMINATIONS. 103 TIIR JIAKINP, AXD TRANSFERKNCI'; OK PURR CULTURES. Ill addition to wliatjhas been said iiiider Pa/Iiogeiiesis^ the following may be of .service to the beginner. For the making of plate cnltnres and for the transfer of organisms from one culture iiiedium to another, select a still da)- and, if possible, a day when a gentle rain or snow is falling. This offers ideal conditions, since the earth is wet, the outside air has been washed free from dust, and there is no wind to stir up
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. now TO AVOID CONTAMINATIONS. 103 TIIR JIAKINP, AXD TRANSFERKNCI'; OK PURR CULTURES. Ill addition to wliatjhas been said iiiider Pa/Iiogeiiesis^ the following may be of .service to the beginner. For the making of plate cnltnres and for the transfer of organisms from one culture iiiedium to another, select a still da)- and, if possible, a day when a gentle rain or snow is falling. This offers ideal conditions, since the earth is wet, the outside air has been washed free from dust, and there is no wind to stir up dust within the laborator^'. A strict adherence to this rule is sometimes veiw inconvenient and it is. Fig. 88.* not meant to be iron-clad. It is, however, of immense service in keeping cultures free from contaminations, and those who propose to disregard it should remember that haste in the beginning of an experiment often leads to vexation and dela)- in the end, especiallv when the success of the experiment depends absolute!}' upon the purity of the culture. *Fic. 88.—Soft rot of gretii cucumbers inoculated by needle-punctures from a pure culture of Bacillus carolovorns. The only parts not softened are those through which the infected needle en- tered i. e., the parts rubbed with mercuric-chloride water. In each a little button of tissue under the disinfected area did not decay. The sound fruit at the right was punctured at the same time, but with a sterile needle. The cucumbers had been removed from the vine, but were not flabby. They were exposed after inoculation to the ordinary air of the laboratory. The photograph was made on the seventh day. About two-fifths natural Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smith, Erwin F. (Erwin Frink), 1854-1927. Washington, D. C. , Carnegie Institu
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