CONTENTS. xiii 
PAG 
Its Real Influence— Other Causes of Modification — ae 
Organic Polarity—Speculative Deductions Concerning 
‘Trees of Life’ in the Past ; Concerning the Resemblance 
of their Products in Different Ages; Concerning the 
greater Extent of this Resemblance amongst the Lowest 
Types ; and Concerning the possibility of the Vertebrate 
Type having been more than once Attained. . . . . 69-76 
IJ..-ON THE TEMPERATURE AT WHICH BACTERIA, VIBRI- 
ONES, AND THEIR SUPPOSED GERMS ARE KILLED WHEN 
IMMERSED IN FLUIDS Ok ExposeD 'ro HEAT IN A 
Moist STATE. 
(From the Proceedings of the Royal Society, No. 143, 1873 ) 
Controversy between the Abbé Spallanzani and Needham— 
Spallanzani’s Conclusions—Overthrow of the Aerial-Con- 
tamination Doctrines—Professor Huxley’s Criticisms — . 
Writers’ Previous Investigations on Vital Resistance of 
Bacteria— Method of Experimentation—Applicable for 
Invisible Germs and for Parent Organisms—Means for 
Lowering Productivity of Organic Fluids—New Inocula- 
tion Experinents—Tabular Results—Conclusions as to 
Degree of Heat which Destroys Bacteria and their Germs 
—Decisive Nature of these Results—Taken in Conjunction 
with other Experiments they Establish the Occurrence of 
‘Spontaneous Generation’ . 2. 6. 6. ee ee 79-97 
JIL.—FuRTHER OBSERVATIONS ON THE TEMPERATURE AT 
WHICH BACTEREA, VIBRIONES, AND THEIR SUPPOSED 
GERMS ARE KILLED WHEN EXPOSED TO HEAT IN A 
Moist STATE; AND ON THE CAUSES OF PUTREFACTION 
AND FERMENTATION. 
(From the Proceedings of the Royal Socity, No. 145, 1873.) 
Different Behaviour of Saline Fluids and Organic Infusions 
when Inoculated—Cause of this Difference—Two-fold 
Composition of Inoculating Material—Its Living and its 
Mere Organic Elements—The Temperature of 140° F, 
