Latent Characters 237 



of other well-known rayed species. Another in- 

 stance may be quoted; it has been pointed out 

 by Grant Allen, and refers to the dead-nettle or 

 Lamium album. Systematically placed in a 

 genus with red-flowering species, we may re- 

 gard its white color as due to the latency of the 

 general red pigment. But if the flower of this 

 plant is carefully examined, it will be found in 

 most cases not to be purely white, but to have 

 some dusky lines and markings on its lower lip. 

 Similar devices are observed on the lip of the 

 allied Lamium maculatum^ and in a less de- 

 gree on the somewhat distant Lamium pur- 

 pureum. With Lamium maculatum or spotted 

 dead-nettle, the affinity is so close that even 

 Bentham united the two in a single species, con- 

 sidering the ordinary dead-nettle only as a va- 

 riety of the dappled purple type. For the sup- 

 port of this conception of a specific or varietal 

 retrograde change many other facts are af- 

 forded by the distribution of the characteristic 

 color and of the several patterns of the lips of 

 other labiates, and our general understanding of 

 the relationships of the species and genera in 

 this family may in a broad sense be based on the 

 comparison of these seemingly subordinate 

 characteristics. 



The same holds good in many other cases, 

 and systematists have often become uncertain 



