1877.] Prof. J. Tyndall on Ferments and Germs. 



355 



all, the particles have been rendered diamagnetically polar ; and secondly, 

 in virtue of the structure impressed upon it, the liquid twists a ray of 

 light in a fashion perfectly determinate both as to quantity and direction. 

 Have the diamond, the amethyst, and the countless other crystals found 

 in the laboratories of nature and of man no structure ? Assuredly they 

 have, though the microscope can make nothing of it. It cannot be too 

 distinctly borne in mind that between the microscopic limit and the 

 true molecular limit there is room for infinite permutations and com- 

 binations." 



It is not without concern that I see the habit of thought and expres- 

 sion against which I thus reasoned revived by so excellent a worker as 

 Dr. Sanderson. My position is, and I think the uniformity of Nature is 

 on my side, that a particle, whether great or small, which when sown 

 produces a plant, is proved thereby to be the germ of that plant ; Dr. 

 Sanderson's position is, that a particle, however fruitful it may be, ceases 

 to be a germ, and dwindles to a " molecular aggregate " when it becomes 

 ultra-microscopical. It may be fairly asked have all microscopes, or only 

 some, the right to define the germ-limit ? Has a pocket-lens the right ? 

 If not, and assuredly it has not, what power of enlargement confers the 

 right? Some of those particles develop into globular Bacteria, some into 

 rod-shaped Bacteria, some into long flexile filaments, some into impetuously 

 moving organisms, and some into organisms without motion. One particle 

 will emerge as a Bacillus anthracis, which produces deadly splenic fever ; 

 another will develop into a Bacterium the spores of which are not to be 

 microscopically distinguished from those of the former organism ; and yet 

 these undistinguishable spores are absolutely powerless to produce the dis- 

 order which Bacillus anthracis never fails to produce. It is not to be ima- 

 gined that particles which, on development, emerge in organisms so dif- 

 ferent from each other, possess no structural differences. But if they 

 possess structural differences they must possess the thing differentiated, 

 viz. structure itself. 



One of the greatest advantages arising from the use of the luminous 

 beam in researches of this nature I considered to be the demonstrative 

 form into which it enables us to throw the argument regarding germs and 

 spontaneous generation. I will here set forth this argument substantially 

 as I stated it in Glasgow last October : — " "We are asked to pronounce 

 on the character of a granular powder placed in the hand. We examine 

 it, but fail to discern what it is. We prepare a bed of earth, sow in it 

 the powder, and soon afterwards find a mixed crop of docks and thistles 

 sprouting from the bed. We repeat the experiment fifty times ; and 

 from fifty different beds, on sowing the powder, we obtain the same crop. 

 What would be our conclusion ? We should not be in a condition to 

 affirm that every grain of the powder was a dock-seed or a thistle-seed ; 

 but we should be in a condition to affirm that both dock- and thistle-seeds 

 formed, at all events, part of the powder. There is not in the range of 



