1 1 2 RETROGRESSION 



common with cultivated plants. 1 Amongst the latter, owing to 

 the fact that offspring are more numerous, especially when it is 

 possible to propagate a favourable individual by means of slips 

 from which seed may be obtained, selection has been more stringent 

 and progression correspondingly rapid. 



184. Now a character (e.g. eye, limb, digestive system) which 

 is old-established is one the usefulness of which has been tested by 

 thousands of generations of continued selection. The permanent 

 usefulness of more recently evolved characters (e.g. special features 

 of prize-breeds) has been less thoroughly tested. They have 

 favoured survival, but have arisen under conditions which, speaking 

 comparatively, may be only temporary. Absolutely new charac- 

 ters (i.e. variations) have not been tested at all, or have been 

 tested for one life only. The fact that characters retrogress with 

 a speed which is inversely proportionate to the length of time 

 during which their usefulness has been proved at once raises a 

 suspicion that we are on the track of a very beautiful and very 



1 " If a considerable number of improved cattle, sheep, or other animals of 

 the same race were allowed to breed freely together, with no selection, but with no 

 change in their conditions of life, there can be no doubt that after a score or a 

 hundred generations they would be very far from excellent of their kind " 

 (Darwin, A nimals and Plants, vol. ii. p. 265). " When selection is suspended, rapid 

 deterioration (from the fancier's standpoint) is the inevitable result. If, e.g., a 

 number of pigeons, good specimens of a distinct breed, are isolated and left un- 

 molested for a few years, they rapidly degenerate, i.e. they lose their show points 

 (be they beaks, frills, ruffs, or metallic tints) and reassume the more fixed char- 

 acters " (Ewart, Presidential Address to Zoological Section of the British Association, 

 1901). In 1810-14 Lady Monk and Lord Gambier collected some plants of the 

 wild heart's -ease and so began the cultivation of the modern pansy. Twenty years 

 after, " a book entirely devoted to this flower was published, and 400 named 

 varieties were on sale " (Animals and Plants, vol. i. p. 392). Half a century later 

 Darwin wrote, " Cultivators speak of this or that kind as being] remarkably con- 

 stant and true ; by this they do not mean, as in other cases, that the kind transmits 

 its characters by seed, but that the individual plant does not change much under 

 culture. The principle of inheritance, however, does hold good to a certain extent, 

 even with fleeting varieties of the Heartsease, for to gain good sorts it is indis- 

 pensable to sow the seeds of good sorts. Nevertheless in almost every large 

 seed-bed a few almost wild seedlings will appear through reversion " (op. cit. t 

 p. 393). At the present time the seed of the pansy " is of such a quality and is 

 saved in so many distinct colours that for all ordinary purposes the trouble of 

 striking cuttings and keeping stocks in pots all the winter through is mere waste 

 of time and pot room" (The Culture of Vegetables and Flowers from Seeds and 

 Roots, issued by Messrs Sutton & Co., p. 195). Messrs Sutton give examples 

 of flowers the varieties of which have been recently fixed by selection carried 

 through many generations. Indeed, any number of similar examples might be 

 given. Mendelian experimenters, however, explain the stability of old-established 

 characters otherwise than by continued selection. We shall discuss their hypo- 

 thesis presently. 



