xxii THE BEGINNINGS OF LIFE. 



Most of those who have worked much at the microscopic 

 investigation of the organisms met with in organic infusions, 

 must have come to the conclusion that there is no break in 

 the continuity of that developmental series which commences 

 with the mere speck of living matter the primordial plastide 

 particle and thence proceeds through such forms as the 

 Bacterium, the Vibrio, the Leptothrix filament, and the myce- 

 lial filament of a microscopic fungus. Not that this is an 

 absolutely necessary order of development, or one which in- 

 variably occurs far from it. But as some Bacteria com- 

 mence their visible existence in the form of plastide particles, 

 so some Vibriones are but the developed representatives of 

 certain Bacteria. And similarly the various kinds of Lep- 

 tothrix filaments grow from certain pre-existing Vibriones, 

 just as certain of these Leptothrix filaments themselves may 

 perchance become modified into larger segmented fungus- 

 filaments, which, under favourable conditions, may fructify 

 and produce spores each of which is capable of develop- 

 ing into an organism, like the parent in its latest phase of 

 evolution. Originating, then, in the form of the minutest 

 visible speck of living matter, it seems almost certain that 



matter whatever their precise origin may have been are practically 

 mere specks of indifferent living matter, having no inherent tendencies, 

 but plastic to the full, and capable of growing into such forms as their 

 environing conditions may determine. And, unless the panspermatists 

 do adopt some such extreme developmental views as these, they will 

 gain comparatively little from the concessions which microscopical in- 

 vestigation compels us to make to them. They will be better able to 

 reconcile their position with the comparative paucity of definite spores 

 and germs which are actually detectable in the atmosphere ; but, if they 

 wish to retain their old notions concerning the distinct and uninterchange- 

 able nature of organic species, they will find it as difficult as ever to ac- 

 count for the fact that the right spores or germs should always be in the 

 right place at the right time. Very little short of a belief that each cubic 

 inch of air contains the germs of myriads of organisms which are known, 

 or which may hereafter be found under previously unknown sets of con- 

 ditions, would be adequate to account for all the observed and observ- 

 able correspondences between the organisms found and the precise 

 nature of the fluids employed. 



