de Fraine .— The Seedling Structure of certain Cactaceae. 175 
A normal diarch root is produced in Rhipsalis Warmingiana , R. 
dissimilis , Echinocereus Ehrenbergii , A. cinerascens , Echinopsis oxygona , 
A. Lagermannii, E. Zuccarinii , Echinocactus bicolor , A. Otlonis, and the 
species of Mamillaria with the exception of AT. missouriensis. 
Theoretical. 
11. The adaptations shown by adult plants in response to their environ¬ 
ment, which have been impressed on the of the young seedling, have 
had a correspondiug influence on their internal structure. 
12. It is not justifiable to use the seedling structure as an indicator of 
phylogenetic connexions. 
