Ill 



Little difference appeared in the rapidity of germination (ger- 

 minative energy) of the two lots in question, the seed requiring 

 about 8-IO weeks under the better conditions. High temper- 

 atures hastened germination, and low ones retarded it, while the 

 final percentages were lowered by both. Alternating temper- 

 atures, with a range of i5°-35° C. (59°-95° F.) or less, simulat- 

 ing the daily fluctuation in nature, proved most efficient in the 

 class of pines possessing the habit of persistence of cones. Of 

 stationary temperatures 35° C. was found to be the best. 

 Although of the six species tested that belong to this class of pines 

 the northern jack pine [P. divavicatd) is the only one that germi- 

 nates equally well at low temperatures, i^vj show a decided lower- 

 ing of their record by high temperatures. The shore pine {P. 

 contorta), probably from California, actually made its best record 

 at a temperature of 20°-50° C. (68°-i22° F.). If nothing more, 

 this at least indicates that the seeds are able to withstand with 

 little injury a rather high degree of dry heat incident to the fires 

 that open the cones. 



Adding an observation on other pine seeds it may be noted 

 that no such deterioration appeared in P. ponderosa and its 

 variety scopidonim in 18 months as Professor Coker finds for 

 P. pahistris. Two tests of the first-named pine six months old 

 germinated 68 and 85 per cent, respectively, while four tests 

 18 months old produced 64, 70, 71, and 85 per cent, of sprouts. 

 The cause for the difference may be partly a matter of storage 

 conditions, and partly an inherent tendency of the species bred 

 by its native climate. In other words, the perishable character 

 of the seed of P. pahistris may be due, wholly or in part, to the 

 warm and humid climate where the species is indigenous. 



REVIEWS. 



Macdonald's Dry Farming* 



This neatly-bound book with nearly forty photographs illus- 

 trating various phases and processes of farming begins with a 

 history of dry farming, which the author claims " has been 



* Macdonald, William. Dry-Farming : Its Principles and Practice. Pp. 290. 

 PI. 37. The Century Co., New York. 1909. 



