472 



Mr. F. Crace-Calvert on the Action of Heat [May 11, 



had been employed in the above experiments was left exposed in similar 

 tubes to its influence, when a large quantity of life was rapidly developed 

 and continued to increase. This result appears to show that the increase 

 of life is not due to reproduction merely, but to the introduction of fresh 

 germs ; for, excepting this fresh supply, there appears to be no reason why 

 life should increase more rapidly in the open than in the closed tubes. 



In concluding this paper I have great pleasure in recognizing the able 

 and persevering attention with which my assistant, Mr. William Thompson, 

 has carried out these experiments. 



III. " Action of Heat on Protoplasmic Life." By F. Crace- 

 Calvert, F.R.S. Received May 9, 1871. 



Those investigators of germ-life who favour the theory of spontaneous 

 generation have assumed that a temperature of 212° Fahr., or the boiling- 

 point of the fluid which they experimented upon, was sufficient to destroy 

 all protoplasmic life, and that the life they subsequently observed in these 

 fluids was developed from non-living matter. 



I therefore made several series of experiments, in the hope that they 

 might throw some light on the subject. 



The first series was made with a sugar solution, the second with an in- 

 fusion of hay, the third with solution of gelatine, and the fourth with 

 water that had been in contact with putrid meat. The hay and putrid- 

 meat solutions were taken because they had often been used by other in- 

 vestigators ; sugar was employed, being a well-defined organic compound 

 free from nitrogen, which can easily be obtained in a state of purity ; and 

 gelatine was used as a nitrogenized body which can be obtained pure and 

 is not coagulated by heat. 



To carry out the experiments I prepared a series of small tubes made of 

 very thick and well-annealed glass, each tube about four centimetres in 

 length, and having a bore of five millimetres. The fluid to be operated 

 upon was introduced into them, and left exposed to the atmosphere for 

 sufficient length of time for germ-life to be largely developed. Each tube 

 was then hermetically sealed and wrapped in wire gauze, to prevent any 

 accident to the operator in case of the bursting of any of the tubes. They 

 were then placed in an oil-bath, and gradually heated to the required tem- 

 perature, at which they were maintained for half an hour. 



Sugar Solution. — A solution of sugar was prepared by dissolving 1 part 

 of sugar in 10 parts of w r ater. This solution was made with common 

 water, and exposed all night to the atmosphere, so that life might impreg- 

 nate it. The fluid was prepared on the 1st of November, 1870, introduced 

 into tubes on the 2nd, and allowed to remain five days. On the 7th of 

 November twelve tubes were kept without being heated, twelve were 

 heated to 200° Fahr., twelve to 300°, and twelve to 400° Fahr. 



