162 BACTERIA IN DAILY LIFE 



space of six hours did not prevent them coming 

 up when sown just as well as ordinary seeds which 

 had not undergone this unique experience ; hence 

 the opportunity of submitting other members of 

 the vegetable kingdom to these low temperatures 

 was eagerly sought for by bacteriologists. Dr. 

 Macfadyen found this opportunity in the labora- 

 tories of the Royal Institution, and, Professor 

 Dewar having placed a generous supply of liquid 

 air and liquid hydrogen at his disposal, he sub- 

 mitted specimens growing in various culture- 

 materials, such as gelatin, broth, potatoes, etc., 

 of typhoid, diphtheria, cholera, anthrax with 

 spores, and other bacteria, for twenty hours and 

 seven days respectively, to a temperature of about 

 - 190 C. In no instance, however, whether ex- 

 posed when growing in fluid or solid media, could 

 any impairment of their vitality or the slightest 

 alteration in their structure be observed. Similar 

 results were obtained when liquid hydrogen, or 

 a temperature of about - 250 C., was applied. 

 The question of the retention or otherwise of the 

 disease-producing powers of these bacteria was 

 not investigated, and in this connection much 

 interest attaches to Mr. Swithinbank's investiga- 

 tions on the vitality and virulent properties of that 

 notorious malefactor amongst micro-organisms, the 

 bacillus tuberculosis, when exposed to the tempera- 



