THE RARE NAKED FORM 



The cactus above shown ("natural size) is closely related to the polar bear cactus — it has even 

 been supposed to be the same species. It grows in the same localities as the hairy form 

 hitherto showri, but is much rarer, and at high altitudes appears to be less thrifty. This 

 suggests that it is unable successfully to compete with the more specialized and better 

 adapted polar bear form, whose long hair gives it an advantage on the high Andean 

 plateau. (Fig. 8.) 



