THE BEGINNINGS OF LIFE. 305 



The facts, therefore, stand in this way. On the one 

 hand it is asserted that pre-existing germs are omni- 

 present, and that they are the precursors of all the 

 living things which teem in infusions and on all 

 varieties of organic matter in a state of decay. Of 

 these living things, by far the most common and widely 

 dispersed are Bacteria , and therefore the hypothesis of 

 Panspermism would require that they should exist most 

 abundantly in the air. But experiments, yielding results 

 of the most indubitable nature, have been performed 

 by Dr. Burdon Sanderson and also by myself, showing 

 that living Bacteria or their germs, whether visible or 

 invisible, do not exist to any appreciable extent in the 

 atmosphere ] . On the other hand, evidence just as con- 

 vincing goes to show that Archebiosis takes place at 

 the present day that Bacteria are constantly arising 

 de novo. And although a recognizable number of the 

 reproductive particles of common Moulds and other 

 microscopic Fungi do exist in the atmosphere, testi- 

 mony of the most conclusive nature also exists con- 

 cerning their independent origin. Such Moulds have 

 been proved to be capable of arising de no'vo within 

 closed flasks, whilst every stage of their heterogenetic 

 origin from the constituents of the c pellicle ' can also 

 be easily watched. Similar modes of origin have also 

 been established for Amcebse and Monads, which are, 

 moreover, not more appreciably represented in the atmo- 

 sphere than the protean forms of Ciliated Infusoria 2 . 



1 See pp. 5-7. 2 See vol. i. p. 443. 



VOL. II. X 



