Plate IV. 



Fig. I.— Growth of Two Colonies in Diameters of B. Phosphorescens 



REPRESENTED GRAPHICALLY. 



(i) In exhausted sealed tube for 13 days, then opened to the air. 

 (ii) In free air for 15 days, then exhausted. 



Dtar 



Daui. o 



Fig. II. — Reproduction of Photographs taken by light emitted by Bacteria 

 after the action of ultra violet light on them at the temperature of liquid 

 air and subsequent heating to the ordinary temperature. 



1. Round tin plate with cut out' cross, bacteria killed where unscreened. 



2. Perforated zinc, showing same effect as above. 



