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PEOGKESS OF MICEOSCOPICAL SCIENCE. 



Experiments on Spontaneous Generation. — Mr. F. Crace-Calvert, 

 F.E.S., lias been recently making some experiments in this direction 

 which have led him to conclude that spontaneous generation is an 

 impossibility. They are published in the ' Proceedings of the Eoyal 

 Society,' No. 128. The more interesting were those made relative 

 to the heat which the lower organisms can tolerate. The first series 

 of experiments was made with a sugar solution. Sugar was employed, 

 being a well-defined organic compound free from nitrogen, which can 

 easily be obtained in a state of purity. To carry out the experi- 

 ments he 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 re- 

 quired temperature, at which they were maintained for half an hour. 

 A solution of sugar was prepared by dissolving 1 part of sugar in 10 

 parts of water. This solution was made with common water, and ex- 

 posed all night to the atmosphere, so that life might impregnate 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 430^ Fahr. The 

 contents of the tubes were microscopically examined on the 1st of 

 December, twenty-four days after heating, with the following re- 

 sults : — 



Sugar Solution 

 not heated. 



Heated for 

 half an hour 

 at 212° Fahr. 



Heated for 

 half an hour 

 at 300° Fahr. 



Heated for 

 half an hour 

 at 400° Fahr. 



Heated for 

 half an hour 

 at 500° Fahr. 



There were ahout 

 thirty animalcules 

 under each field 

 of the microscope, 

 principally &viall 

 black vibrios, two 

 or three micro- 

 zynies swimming 

 slowly about, three 

 or four ordinary 

 swimming vibrios, 

 and a few Bac- 

 teria. 



A great portion 

 of the life had 

 disappeared ; no 

 animalcules were 

 swimming ; still 

 this temperature 

 had not completely 

 destroyed life. Four 

 or five small black 

 vibrios were ob- 

 served moving 

 energetically to 

 and fro ; two or 

 three ordinary vi- 

 brios were also 

 observed moving 

 energetically in 

 the same position 

 of the field; that 

 is, without swim- 

 ming about. 



The sugar was 

 slightly charred, 

 but the life was 

 not entirely de- 

 stroyed, as one or 

 two ordinary vi- 

 brios and one or 

 two small black 

 vibrios were ob- 

 served in motion 

 under the field of 

 the microscope. 



The sugar was 

 almost entirely 

 decomposed ; no 

 trace of life was 

 observed. 



No life observed. 



