126 THE FLOATING-MATTER OF THE AIR. 



Ro case of pseudo-spontaneous generation ever 

 occui^^ed under my hands that was not to be accounted 

 for in an equally satisfactory manner. 



In this inquiry, thus far, I have confined my ob- 

 servations to purely liquid infusions, purposely exclud- 

 ing milk, mixtures of turnip-juice and cheese, and, 

 indeed, mixtures of solids and liquids of all kinds. The 

 next section of the investigation will be devoted to these 

 and kindred subjects; and to it I also postpone the 

 complete examination oi pepton, and of the remarkable 

 experiments described by Dr. William Eoberts, a small 

 residue of which only I have failed to corroborate. 



Throughout the whole of this investigation I have 

 had to congratulate myself on the zealous and efficient 

 aid of ray excellent assistant, Mr. John Cottrell. His 

 intelligence in seizing my ideas, and his mechanical 

 skill in realizing them, have rendered me admirable 

 service. Without such aid, indeed, so much ground 

 could not have been covered in the time. 



Royal Institution, 5th April, 1876. 



It gives me special pleasure to direct attention here 

 to a paper by the Eev. W. H. Dallinger, for an advanced 

 proof of which I am indebted to the courtesy of Dr. 

 Lawson, editor of the ' Popular Science Eeview.' Mr. 

 Dallinger and his colleague Dr. Drysdale are known to 

 have pushed the microscope to its utmost power of per- 

 formance at the present time. Their ' Researches into 

 the Life-History of the Monads ' are models of scientific 

 thoroughness and concentration. Mr. Dallinger's review 

 of the present position of the doctrine of spontaneous 

 generation, his remarks on Bacterial germs in relation 



