THE PATH OF EVOLUTION 



compounds that serve to warn off and to keep away 

 the living, to whom the bacteria and the immediate 

 products of decomposition would be injurious. After 

 their work is done the bacteria are carried off in the 

 water, or when dried blown about and scattered again 

 throughout the world. All that finally remain of 

 the organism are some nitrates and some little earthy 

 substances that the living body had gathered in. 

 Dust and Ashes ! 



The Bacteria are the smallest of known organized 

 beings : the largest of them are not over -^ of an 

 inch iii diameter, the smallest less than ~. They 

 consist of protoplasm, and have the shape of sphe- 

 roids, or of short cylinders, rods, and threads. Of 

 these, some are straight, others bow-shaped, curved 

 or spiral. The exterior, when moist, is gelatinous, 

 but when dried becomes like a crust. They grow 

 and multiply with astonishing rapidity in fluids suit- 

 able for their nourishment. The rod-like shapes 

 extend in length, and then divide into two equal 

 parts each half again dividing, when a certain 

 length is attained. Under favorable conditions, in 

 most varieties, spores or germs are formed. These are 

 spherical, with thick walls, and refract light strongly. 

 It has been observed that a new formed bacterian 

 cell within twenty minutes will so increase in length 

 as to reach the limit of its normal growth ; then it 



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