ADDRESS. Ixxix 



It must be borne in mind that even if we are satisfied from a persevering 

 and impartial inquiry that organic forms have varied indefinitely in time, 

 the cmisa causans of these changes is not explained by our researches ; if it be 

 admitted that we find no evidence of amorphous matter suddenly changed 

 into complex structure, still why matter shoidd be endowed with the plasticity 

 by which it slowly acquires modified structure is imexplained. If we assume 

 that natural selection, or the struggle for existence, coupled with the tendency 

 of like to reproduce like, gives rise to various organic changes, still our re- 

 searches are at present uninstructive as to why like should produce Hke, why 

 acquired characteristics in the parent should be reproduced in the offspring. 

 Reproduction itself is stUl an enigma, and this great question may involve 

 deeper thoughts than it would be suitable to enter upon now. 



Perhaps the most convincing argument in favour of continuity which could 

 be presented to a doubting mind would be the difl[iculty it would feel in 

 representing to itself any per saltiim act of nature. Who would not be 

 astonished at beholding an oak tree spring up in a day, and not from seed or 

 shoot ? We are forced by experience, though often miconsciously, to believe 

 in continuity as to aU effects noAV taking place ; if any one of them be ano- 

 malous we endeavour, by tracing its history and concomitant circumstances, 

 to find its cause, i. e. to relate it to antecedent phenomena ; are we then to 

 reject similar inquu-ies as to the past ? is it laudable to seek an explanation 

 of present changes by observation, experiment, and analogy, and yet repre- 

 hensible to apply the same mode of investigation to the past history of the 

 earth and of the organic remains embalmed in it ? 



If we disbelieve in sudden creations of matter or force, in the sudden 

 formations of complex organisms now, if we now assign to the heat of 

 the sun an action enabHng vegetables to live by assimilating gases and amor- 

 phous earths into growing structures, why should such effects not have taken 

 place in earher periods of the world's history, when the sun shone as now, 

 and when the same materials existed for his rays to fall upon ? 



If we are satisfied that continuity is a law of nature, the true exjiression 

 of the action of Almighty Power, then, though we may humbly confess our 

 inability to explain why matter is impressed with this tendency to gradual 

 structural formation, we should cease to look for special interventions of 

 creative power in changes which are difficult to understand, because, being 

 removed from us in time, their concomitants are lost ; we should endeavour 

 from the relics to evoke their history, and when we find a gap not try to 

 bridge it over with a miracle. 



If it be tnie that continuity pervades all physical phenomena, the doctrine 

 applied by Cuvier to the relations of the different parts of an animal to each 

 other might be capable of great extension. All the phenomena of inorganic 

 and organized matter might be expected to be so inter-related that the study 

 of an isolated phenomenon would lead to a knowledge of numerous other phe- 

 nomena with which it is connected. As the antiquary deduces from a monolith 

 the tools, the arts, the habits, and epoch of those by whom it is wrought, so 

 the student of science may deduce from a spark of electricity or a ray of light 

 the source whence it is generated ; and by similar processes of reasoning other 

 phenomena hitherto unknown may be deduced from their probable relation 

 with the known. But, as with heat, light, magnetism, and electricity, though 

 we may study the phenomena to which these names have been given, and 

 their mutual relations, we know nothing of what they are ; so, whether we 

 adopt the view of natural selection, of effort, of plasticity, &c., we know not 

 why organisms shoidd have this nisus formativus, or why the acquired habit 

 or exceptional quality of the individual shoixld reappear in the offspring. 



