1878.] by Light on Organic Infusions. 213 



turnip infusion. Before sealing they had been boiled for five minutes 

 in the laboratory of the Royal Institution. They were carefully 

 packed in sawdust, but when unpacked the fragile sealed ends of 

 about 20 of them were found broken off. Some of these injured 

 flasks were empty, while others still retained their liquids. The 80 

 unbroken flasks were found pellucid, and they continued so throughout 

 the summer. All the broken ones, on the other hand, which had 

 retained their liquids, were turbid with organisms. 



Shaking up the sawdust, which I knew must contain a considerable 

 quantity of germinal matter, I snipped off the ends of a number of 

 flasks in the air above the sawdust. Exposed to a temperature of 70° 

 or 80° F., the contents of all these flasks became turbid in two or 

 three days. 



The experiment was repeated ; and after the contaminated air had 

 entered them, I exposed the flasks to strong sunshine for a whole 

 summer's day; one batch, indeed, was thus exposed for several 

 successive days. Placed in a room with a temperature of from 70° 

 to 80° F., they all, without exception, became turbid with organisms. 



Another batch of flasks, after having their sealed ends broken off, 

 was infected by the water of a cascade derived from the melting of 

 the mountain snows. They were afterwards exposed to a day's strong 

 sunshine, and subsequently removed to the warm room. In three 

 days they were thickly charged with organisms. 



On the same day a number of flasks had their ends snipped off in 

 the open air beside the cascade. They remained for weeks trans- 

 parent, and doubtless continue so to the present hour. 



I do not wish to offer these results as antagonistic to those so 

 clearly described by Dr. Arthur Downes and Mr. Thomas Blunt, in 

 the "Proceedings of the Royal Society," for December 6th, 1877.* 

 Their observations are so definite that it is hardly possible to doabt 

 their accuracy. But they noticed anomalies which it is desirable to 

 clear up. On the 10th of July, for example, they found 9 hours' 

 exposure to daylight, 3\ hours of which only were hours of sunshine, 

 sufficient to effect sterilization ; while, on the 29th of July, " a very 

 hot day, with much sunshine," 11 hours' exposure, "9 of which were 

 true insolation," failed to produce the same effect. Such irregu- 

 larities, coupled with the results above recorded, will, I trust, induce 

 them to repeat their experiments, with the view of determining the 

 true limits of the important action which those experiments reveal. 



* Yol. xxvi, p. 488. 



VOL. XXVIII. 



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