PREFACE. 
Vll 
Lionel Beale, F.R.S., has called “the Mystery of Life ” ; 
upon which Professor G. G. Stokes, F.R.S., no mean 
authority among scientific men (see Nature, No. 298), 
recently remarked (in his Address as President of the British 
Association in 1872) : — 
“ What this something, which we call Life, may be, is a profound mystery. 
W e know not how many links in the chain of secondary causation may yet 
remain behind ; we know not how few. It would be presumptuous indeed 
to assume in any case that we had already reached the last link, and to 
charge with irreverence a fellow- worker who attempted to push his investi- 
gations yet one step further back. On the other hand, if a thick darkness 
enshrouds all beyond, we have no right to assume it to be impossible that 
we should have reached even the last link of the chain, a stage where 
further progress is unattainable ; and we can only refer the highest law at 
which we stopped to the fiat of an Almighty Power. To assume the 
contrary as a matter of necessity, is practically to remove the First Cause of 
All to an infinite distance from us. The boundary, however, between what 
is clearly known and what is veiled in impenetrable darkness is not ordi- 
narily thus sharply defined. Between the two there lies a misty region, in 
which loom the ill-discerned forms of links of the chain which are yet 
beyond us : but the general principle is not affected thereby. Let us fear- 
lessly trace the dependence of link on link as far as it may be given us to 
trace it, but let us take heed that in thus studying second causes we forget 
not the First Cause, nor shut our eyes to the wonderful proofs of design 
which, in the study of organized beings especially, meet us at every turn. ” 
F. PETRIE, 
Hon. Sec. and Editor. 
December 30, 1S76. 
