226 Retrograde Varieties 



tematist, Alphonse De Candolle, we may now 

 try to give the proofs of our assertion, by using 

 only those instances that have been thoroughly 

 tested in every way. 



We may at once proceed to the retrogressive 

 or negative varieties. The arguments for the 

 assumption that elementary species owe their 

 origin to the acquisition of new qualities may 

 well be left for later lectures when we shall 

 deal with the experimental proofs in this mat- 

 ter. 



There are three larger groups of facts, on 

 which the assumption of latent characters in 

 ordinary varieties rests. These are true ata- 

 vism, incomplete loss of characters, and system- 

 atic affinity. Before dealing with each of these 

 separately, it may be as well to recall once more 

 that in former lectures we have treated the 

 apparent losses only as modifications in a 

 negative way, without contemplating the under- 

 lying causes. 



Let us recall the cases of bud-atavism given 

 by the whitish variety of the scarlet Ribes, by 

 peaches and nectarines, and by conifers, includ- 

 ing Ceplialotaxus and Cryptomeria. These and 

 many other analogous facts go to prove the re- 

 lation of the variety to the species. Two as- 

 sumptions are allowable. In one the variety 

 differs from the species by the total loss of the 



