Latent Characters 221 



broader view of the whole evolution of the 

 vegetable kingdom. It is manifest that highly 

 developed plants have a larger number of 

 characters than the lower groups. These 

 must have been acquired in some way, during 

 preceding times. Such evolution must evident- 

 ly be called a process of improvement, or a 

 progressive evolution. Contrasted to this is the 

 loss, or the latency of characters, and this may 

 be designated retrogressive or retrograde evo- 

 lution. But there is still a third possibility. 

 For a latent character may reassume its ac- 

 tivity, return to the active state, and become 

 once more an important part of the whole or- 

 ganization. This process may be designated 

 as regressive evolution; it obviously completes 

 the series of the general types of evolution. 



Advancement in general in living nature de- 

 pends on progressive evolution. In different 

 parts of the vegetable kingdom, and even in 

 different families this progression takes place 

 on different lines. By this means it results in 

 an ever increasing divergency between the sev- 

 eral groups. Every step is an advance, and 

 many a step must have been taken to produce 

 flowering plants from the simplest unicellular 

 algae. 



But related to, and very intimately con- 

 nected with this advancement is the retrogres- 



