■ VI BIOLOGICAL SOCIETY OF WASHINGTON. 



tive. It was this type, and not the true pines and firs, that 

 represented the conifers during the Jurassic period when the 

 cycadean vegetation predominated over all other forms. And 

 yet this solitary survivor of that long line of ancestors, this 

 waning, tottering, dying ginkgo, with its perfect nut and ample 

 deciduous foliage, may be properly regarded as the highest 

 type of conifers, while the pines, spruces, and junipers must be 

 looked upon as somewhat lower types, persisting according to 

 the law already explained. 



Angiospermy . — The next great step was from gymnospermy 

 to angiospermy, the beginnings of which are buried in obscu- 

 rity. In the gymnosperm the tender developing ovule and 

 maturing seed is exposed to even- rude element that besets the 

 life of a plant. Thus exposed it is impossible for it to attain 

 that delicacy of organization necessary to the highest perfec- 

 tion of vegetable growth. Protection of the germ thus early 

 became the great desideratum. When it was first attained we 

 know not, but there are some uncertain indications that angio- 

 spermous plants existed in Carboniferous time. But if so they 

 did not belong to the higher or exogenous types. The strug- 

 gles for the protection of the trunk on the one hand, and for 

 the protection of the germ on the other, were independent 

 struggles. Progress toward exogeny had nothing to do with 

 progress toward angiospermy, and if the latter was attained 

 during Carboniferous or early Mesozoic time it was attained 

 only by endogenous plants, and the earliest angiosperms were 

 endogeus and not exogens. That is, the lower type from the 

 standpoint of internal structure became the higher type from 

 the standpoint of floral structure. Progress could therefore 

 only be slow. What was gained by the one was lost by the 

 other. Not until both these steps should be taken by the same 

 type of plants could any new departure take place, and the 



