SURFACE STERILIZATION. 



IOQ 



washed with equal care in sterile distilled water. Wlu-n many inoculations are 

 made with lar^e numbers of check plants and when dne care has been taken to 

 work under conditions such that accidental contaminations from the same organ- 

 isms are not to be feared, the writer has not found this precaution necessary. The 

 use of mercuric chloride should be avoided, if possible, especially on leaves, as the 

 writer's experiments have shown that it penetrates into the plant (some plants) for 

 a considerable distance and prevents the action of the bacteria to this extent (fig. 

 88), if not altogether, as has happened in some cases. 



THE KEEPING OF RECORDS. 



If one contemplates doing much work, a careful record of what has been done 

 is as important as the experiment itself, since exact remembrance is certain to pass 

 away with lapse of time. 



In all his work, the student should accustom himself to make very exact 

 statements, so that others may be able to follow him. For example, he should 

 not describe his organism as "yellow" or "red" without qualifications, since there 

 are many yellows and reds, but should carefully compare it with some standard 

 color-scale (Ridgway's, Saccardo's, Standard Dictionary, etc.), and govern himself 



accordingly. He should not say, 

 " Organism does not grow at 

 room-temperatures," but rather 

 should state the temperature at 

 which growth does not occur, as 

 15, 25, or 35 C., anyone of 

 which may be "room-tempera- 

 ture," depending on the latitude > 

 altitude, and time of year. He 

 should not say, " Organism is 

 killed at temperature of 65 C.," 

 without at the same time stating 

 the age of the culture, condi- 



Fig. 94.* 



tions of exposure, and time required, which might be ten days or five minutes. 



Every independent worker will in the end devise a method of note-taking which 

 is more or less characteristic of his personal peculiarities and best adapted to his 

 own particular needs. For all persons there is no one best method. The methods 

 described in the following paragraphs have been settled upon as those most con- 

 venient for the writer, but it does not follow that they are the most economical of 

 time, or the best devisable, or the ones which independent workers should follow. 

 They are here given as hints for beginners and because the method a man employs 

 in his work is always a matter of more or less interest to his fellow-workers. 



First of all, there should be provided a record book in which the method of 

 preparation of each culture medium is carefully described. This should be a good- 



l ; i.,. Q4. Hand-sprayer which may lie used for distributing bacteria on plants. Some form is 

 usually kept in every pharmacy and sold as a cologne atomizer. 



