Cold-Resistance in Spineless Cacti 



133 



SmmSm««^«»^ 



Fig. 1 . — Curve showing cooling point, freezing point and'duration of freezing point of 



Opuntia Ellisiana. 



/'♦ *' ♦o *•' 



r ^ J ■' 



Fig. 8. — Curve showing cooling point, freezing point, and duration of freezing point of 



Opuntia sp. Burbank Special. 



