282 FRAGMENTS OF SCIENCE 



cernment, but which, nevertheless, has the most important 

 bearing on the welfare of the higher life-world. 



And now let us reason together as regards the origin 

 of these bacteria. A granular powder is placed in your 

 hands, and you are asked to state what it is. You exam- 

 ine it, and have, or have not, reason to suspect that seeds 

 of some kind are mixed up in it. To determine this point 

 you prepare a bed in your garden, sow in it the powder, 

 and soon after find a mixed crop of docks and thistles 

 sprouting from your bed. Until this powder was sown 

 neither docks nor thistles ever made their appearance in 

 your garden. You repeat the experiment once, twice, ten 

 times, fifty times. From fifty different beds after the sow- 

 ing of the powder, you obtain the same crop. What will 

 be your response to the question proposed to you? "I 

 am not in a condition," you would say, "to afiirm that 

 every grain of the powder is a dock-seed, or a thistle- 

 seed; but I am in a condition to affirm that both dock 

 and thistle seeds form, at all events, part of the powder.'* 

 Supposing a succession of such powders to be placed in 

 your hands with grains becoming gradually smaller, until 

 they dwindle to the size of impalpable dust particles; as- 

 suming that you treat them all in the same way, and 

 that from every one of them in a few days you obtain 

 a definite crop — it may be clover, it may be mustard, 

 it may be mignonette, it may be a plant more minute 

 than any of these, the smallness of the particles, or of 

 the plants that spring from them, does not afEect the 

 validity of the conclusion. Without a shadow of mis- 

 giving you would conclude that the powder must have 

 contained the seeds or germs of the life observed. There 

 is not in the range of physical science an experi- 



