494 



Dr. A. Downes and Mr. T. P. Blunt on [Dec. 6 } 



rods and dumb-bells in great numbers, and an abundance of the micro- 

 cocci associated with the ammoniacal fermentation of urea. The reaction 

 was alkaline. Prolonged insolation, it may be noted, had a bleaching 

 effect on the urinary colouring-matter. 



Most of our preliminary observations have been made with Pasteur's 

 solution and with urine, but more recently we have experimented on some 

 hay-infusion. 



Obs. 11. Sept. 22. — Three capillary tubes were filled with infusion 

 made from some very old hay. One end of each was sealed off, the other 

 end haring a small plug of cotton wool. The infusion was of a deep 

 yellow-brown colour. Two of the tubes (a) were insolated, and one (b) 

 encased. 



A portion also of the infusion was boiled for five minutes in a test- 

 tube, the mouth of which was closed during ebullition with cotton wool, 

 the tube (which was labelled c) being then placed in the dark. 



Oct. 7. — Each sample was closely examined under the microscope. In 

 the encased tube h large numbers of moving rod-like Bacteria were seen ; 

 but in the insolated tubes a a very few moving particles alone were visible 

 to an immersion . The solution c, which had been boiled, contained a 

 large number of rods, of greenish tint, with slightly clubbed refractive 

 ends, for the most part motionless, and usually single. Xone of these 

 were observed in the capillary tubes. 



In some observations with turnip-infusion made in May last we found 

 that while it became extremely rotten and offensive in those tubes which 

 were encased, in corresponding tubes exposed to the light it was com- 

 paratively odourless, although the development of the Bacteria had not 

 been wholly prevented. 



Judging from the following experiment with zymase, light would not 

 appear to exercise any retarding influence on the " indirect ferments." 



Obs. 12. — Some yeast water, four or five times filtered, was mixed with 

 weak syrup (which previously to the experiment was proved to have 

 scarcely any action on Pehling's solution) and placed in two test-tubes. 

 One was encased in the usual way, the other was exposed for two hours 

 to full daylight, including about three quarters of an hour of direct 

 sunlight. 



At the end of this time, 



25 grain measures of Pehling's solution were reduced by 110 grain 



measures of the insolated liquid. 

 25 grain measures of Pehling's solution were reduced by 112 of the 

 solution from the encased tube. 



These results may be regarded as being, within the limit of experi- 

 mental error, practically the same. 



What is the true account of this influence of light ^vhich has been 

 shown to act so destructively on organisms by no means deficient in their 

 tenacity of life ? We do not profess to enter into this question at pre- 



