1898.] MICROSCOPICAL JOURNAL. 81 



72,000 tons. Extensive losses by souring have led to 

 careful bacteriolog-ical studies. By examining- cans it was 

 found that sound cans were sterile and that spoiled ones 

 produced by pure culture twelve different species of 

 bacteria — 11 bacilli and one micrococcus. It is believed 

 that they transform the saccharine and starchy matter 

 into org-anic acids or other substances of disagreeable 

 taste or oder. Sterile cans inocculated with these organ- 

 isms promptly became sour. A vacuum is not necessary 

 for keeping canned corn for air properly sterilized does 

 not harm the contents. This has been indisputably 

 proven by a long line of experiments. Moreover some 

 bacteria can develope in a vacuum so that the latter is not 

 a sure protection. Sterilization and not air-dissipation is 

 the protection sought. Prescott and Underwood have 

 spent a whole season with the best appliances in canning 

 establishments and have practically settled these difficult 

 questions. They found after extensive labor that heating 

 for 10 minutes to 121 deg. C (250 deg. F) would sterilize 

 corn in two-pound cans. The resistance of bacteria to 

 boiling is such that some survive 5 hours boiling, others 

 survive 8 hours boiling temperature. The ordinary water 

 bath is thus proven useless. By culture methods and 

 microscopical examination it was found that the bacteria 

 were present on the kernels of corn when they came from 

 the field and were in the new cans even after 30 minutes 

 in boiling water and those so found were of the same 

 species as those found in sour corn. Their rate of growth 

 is enormous and appalling. Streak-cultures showed fre- 

 quentlv a well-marked growth in 4 to 6 hours. Their 

 multiplication was found to be facilitated by warm, moist 

 weather. The new bacilli discovered require 12 pages of 

 descriptions and the 13 photo-micrographs presented with 

 the paper show plate cultures of the various forms of 

 much interest. The March number of the Technological 

 Quarterly is referred to for further particulars. 



Collecting Plankton. — Dr. Dolley has devised a large 

 centrifugal machine which may be driven by hand or by 

 motor. It quickly separates all the suspended matter. 



