ORIGIN OF LIFE. 53 
’ The second hypothesis may be said to be based 
'/upon (rather than merely supported by) the analogy, 
tion’ amongst living things. It is argued that if all 
Ij from the observed universality of ‘reproduc- 
Br) if 
\\ 
\ 
| 
\ 
| 
a ce 
living things, as far as the process is visible, are 
‘reproduced’ or derived from pre-existing parent 
iving things, so, it is probable that cases in which 
the process is invisible would come under the same 
i 
i 
. .| otherwise universal law—expressed by the phrase 
omne vivum ex vivo. 
But this formula, which has now become a party 
mt watchword, bases its supposed universality and 
| 
| authority, partly (2) upon a simple and incomplete 
_ observation of phenomena, and partly (%) upon an 
4 
‘erroneous assumption. 
(a). On the side of observation the formula omne 
vivum ex vivo is supposed to derive its authority from 
the fact that the experience of mankind generally— 
both skilled and unskilled—testifies to its truth. 
Here, however, the authority of the formula is in- 
validated, on account of a grave misapprehension 
as to the real nature of the problem. It is almost 
unnecessary to say that observation is of no avail 
in regions where it becomes impossible, and conse- 
quently that observation cannot tell us whether 
previously invisible specks of living matter have 
arisen from invisible living germs or by an inde- . 
