322 FKAGMENTS OF SCIENCE. 



when infected with the germs of desiccated hay, were 

 completely broken down by this method of discontinuous 

 heating, three minutes being found sufficient to accom- 

 plish what three hundred minutes' continuous boiling 

 failed to accomplish. I applied the method s moreover, 

 to infusions of various kinds of hay, including those 

 most tenacious of life. Not one of them bore the 

 ordeal. These results were clearly foreseen before they 

 were realised, so that the germ theory fulfils the test 

 of every true theory, that test being the power of 

 prevision. 



When ' naked or almost naked specks of protoplasm ' 

 are spoken of, the imagination is drawn upon, not the 

 objective truth of Nature. Such words sound like the 

 words of knowledge where knowledge is really nil. The 

 possibility of a ' thin covering ' is conceded by those who 

 speak in this way. Such a covering may, however, 

 exercise a powerful protective influence. A thin pellicle 

 of india-rubber, for example, surrounding a pea keeps 

 it hard in boiling water for a time sufficient to 

 reduce an uncovered pea to a pulp. The pellicle pre- 

 vents imbibition, diffusion, and the consequent dis- 

 integration. A greasy or oily surface, or even the layer 

 of air which clings to certain bodies, would act to some 

 extent in a similar way. ' The singular resistance of 

 green vegetables to sterilisation/ says Dr. William 

 Roberts, ' appears to be due to some peculiarity of the 

 surface, perhaps their smooth glistening epidermis 

 which prevented complete wetting of their surfaces.' 

 I pointed out in 1876 that the process by which an 

 atmospheric germ is wetted would be an interesting 

 subject of investigation. A dry microscope covering- 

 glass may be caused to float on water for a year. A 

 sewing-needle may be similarly kept floating, though 

 its specific gravity is nearly eight times that of water. 



