BOOK IV. 



DEVIATIONS FROM THE ORDINARY SIZE AND 

 CONSISTENCE OF ORGANS. 



In the animal kingdom the entire adult organism, as 

 well as each of its separate pa^ts, has certain dimen- 

 sions, beyond which, under ordinary circumstances, it 

 does not pass, either in the one direction or the other. 

 It may not be easy or possible to state what the limits 

 are, but, practically, this inability to frame a precise 

 limitation is productive of no inconvenience. It is 

 universally admitted that a certain animal attains such 

 and such dimensions, and that one organ has a certain 

 proportionate size as contrasted with another. The same 

 rules hold good in the case of plants, though in them 

 it is vastly more difficult to ascertain what may be 

 called the normal dimensions or proportions. Never- 

 theless observation and experience soon show what 

 may be termed 'the average size of each plant, and any 

 disproportion between the several organs is speedily 

 detected. 



When there is a general reduction in size throughout 

 all the organs of a plant, or throughout all the nutritive 

 organs, stem, leaves, &c., and the several portions par- 

 ticipate in this diminished size, we have what are gene- 

 rally termed " dwarf varieties," dwarf in comparison, 

 that is, with the ordinary condition of the plants ; on 

 the other hand, if the entire plant, or, at least, if the 



