THE AMERlCAxN BOTANIST 43 



Cha.nckabij-: Cactus. — From iIk- desert region of we.sl- 

 ern Arizona Mr. James H. Ferris sends us a specimen of cactus 

 whose Color-transformations are a strong soiu'ce of interest. 

 The [)lant is a globular species thickly set with stout grayish 

 thorns that must render it \ery inconspicuous in its de>ert 

 home. The instant that rain touches it, iKnvever. il becomes 

 a ball of flaming crimson and one of the most cons[)icuous and 

 iKuulsome plants in existence- Investigation sh(jw> that 

 tlie thorns are really a deep red but so heavily covered on botli 

 surfaces with a forest of waxy columns that the c<jlor is mask- 

 ed. When water falls on the tliorns, however, the wax be- 

 comes nearly transparent and the deep red, shining through 

 produces the change noted. 



High Growth Temperatures. — A number of simple 

 plants are known that are able to exist in hot springs whose 

 waters are nearly at the boiling point, but more complex formr 

 of vegetation are ([uickly killed at such temi)eratures ; in fact 

 a temperature of 122° Fahrenheit (50° C. ) is regarded a.-> 

 fatal. Some forms of cacti, however, seem not only resistant 

 to dessication but to heat as well. In a recent number of 

 Science, a report from the Desert Botanical Laboratory in 

 .-\rizona notes that joints of a hardv Of^iintia or "pricklv 

 pear" were obserxed to continue growth in a temperature of 

 136° F. either plants subjected to a temperature of 144 F. 

 resumed growth when the temj)erature was again l(.-were(l. 

 This is the limit for acti\e protoplasm, so far as known, and 

 it ai)parently is not likely to be much e.xceeded. 



Navajo Kve.mxc. 1'ki.mrosk. — Those who are interested 

 in the evening primroses may be glad to know that ihev can se- 

 cure seeds of the Navajo species from this office for ten cents 

 a packet. We shall be glad to exchange for .seeds or plants of 

 other primroses from the Great Plains region. 



