350 Messrs. Cross and Bevan on the Correlation of 



worthy the name, life was or is regarded as any thing more 

 than a rearrangement and special disposition of the preex- 

 isting: it cannot be doubted that life, as known on this planet, 

 had a beginning ; nor, further, that the whole analogy of the 

 origin of subsequently derived life points to it as an indivi- 

 dual and special phenomenon. In a word, the doctrine of 

 Spontaneous Generation has been expunged from biological 

 science ; and a revival of its analogue from the point of view 

 of chemical science we hold to be groundless. Not only so, 

 but, to give a more practical expression to these views, a 

 loose adoption of the non-belief in a special vital force will 

 materially impede progress in the domain of biological che- 

 mistry. We cannot find a stronger proof of the want of 

 recognition of the special and peculiar nature of the chemical 

 phenomena of life than in the preyalence of empirical methods 

 for the resolution of plant substances, their empiricism con- 

 sisting chiefly in their unreasoned foundations upon the me- 

 thods of separation of inorganic substances. To this portion 

 of the science our attention has been specially directed; and 

 we proceed to discuss it in certain of its bearings upon the 

 main subject of this paper. 



The work of the plant, considered in its intrinsic results, is 

 to grow, to form tissues and organs ; a side issue of growth 

 is the elaboration of substances which subserve future growth; 

 and a subsidiary result is the formation of certain substances 

 which we may regard as excreta, as unavailable for the main 

 end. These excreta are often bodies of well-defined physical 

 properties, of more or less simple molecular structure, whose 

 constitution is so far comprehended as to allow of their syn- 

 thetical production in the laboratory. For the isolation of 

 such bodies, methods founded upon the fixity of their consti- 

 tution are general and satisfactory. But, on the other hand, 

 substances whose essential condition is that of continual dif- 

 ferentiation, whose constitution is but little understood even 

 when viewed statically, whose relationship to the former group 

 is probably of a parental character, should be treated with 

 due regard to these distinctions : indeed it seems hopeless to 

 attempt to comprehend their chemical functions in disregard 

 of these their special biological correlations. The neglect of 

 these considerations has led to the adoption of empirical and, 

 to that extent, arbitrary methods of analysis and classification; 

 names have been multiplied to individualize bodies which, 

 occurring in a developmental series, should have received a 

 corresponding general or group definition; and much time and 

 capability have been spent in establishing facts before their 

 probable and relative value had been taken into consideration. 



