236 THE FLOATING-MATTEE OF THE AIR. 



temperature of 70° Fahr. An unboiled sample of every 

 seed was sown at the same time beside the boiled ones. 

 The unboiled seeds sprouted vigorously. Thirty seconds' 

 exposure to the boiling temperature deprived both the 

 peas and the beans of their power of germination. A 

 few of the cress-seeds exposed for this interval sprouted, 

 but the majority were killed, and all were killed by a 

 minute's boiling. On the other hand, a very large pro- 

 portion of the mustard-seeds boiled for thirty seconds 

 germinated. The time of exposure in the case of this 

 seed was doubled, trebled, and quadrupled, leaving stili 

 a residue of life. The fertile mustard-seeds gradually 

 diminished in number as the time of boiling increased, 

 but even after two minutes' boiling many of them 

 germinated. 



And now comes a fact which I deem of some im- 

 portance as regards the present inquiry. When the 

 calico bag was abandoned, and the mustard-seeds were 

 placed loosely in water, so as to ensure not only the free 

 communication to them of its temperature, but free 

 diffusion between the soluble portions of the seeds and 

 the surrounding liquid, not one of them escaped the 

 ordeal of thirty seconds' boiling. In the first series of 

 experiments, the bag which held the seeds together not 

 only exercised a protecting influence itself, but it en- 

 abled the outside seeds to act as shields to the inside 

 ones Assuredly in a far higher degree will cheese 

 shield germs contained within it. Unlike fruit and 

 meat, it is highly impervious to water. It tluis wards 

 off the liquid on which the softening and swelling of the 

 germ depend, so tliat within such a substance the life of 

 a germ might be indefinitely prolonged. 



