310 BOTANICAL GAZETTE [October 



Another paper by the same authors'* describes some experiments made to 

 test the effects of desiccation on vitahty of seeds. The seeds of grains and 

 grasses will withstand drying to less than i per cent without material loss in 

 germination. Blue grass and Johnson grass can even be dried to o.i per cent 

 of moisture without loss in germination, but vigor is greatly reduced in the blue 

 grass. Still further loss of vigor occurred in the blue grass when dried in 

 vacuo at ioo° C. for 6 hours, but the germination percentage was not materially 

 reduced. These results negative the statements of Ewart that excessive dry- 

 ing changes dormant protoplasm to such an extent that the essential molecular 

 groupings cannot be re-established under conditions for germination. — C. A. 

 Shull. 



Curing timber. — A method of drying timber more uniformly to avoid 

 cracks and shakes in the logs is proposed by Stone.^ The method is based upon 

 assumptions as to the natural movement of sap in trees which will not meet 

 with favor among plant physiologists. He considers that the water is held in 

 the saturated tracheal walls, evaporates from these walls into continuous vapor- 

 filled lumina, and moves upward through the tubes in response to a partial 

 vacuum produced above by transpiration. Indeed, the water is supposed to 

 travel upward mostly by night, because at that time the leaves are much cooler 

 than the trunk, and would condense the vapor from the tubes, thus fiUing the 

 cells as reservoirs against the next day's transpiration. Salts are imagined 

 to travel through the cell walls of the tracheae rather than in the transpiration 

 stream, which is nonexistent in Stone's assumption. It is hard to imagine 

 a conception much more at variance with experimental results of physiological 

 studies. 



The actual drying plant suggested is a closed shed, arranged with a cooler 

 at one end, the purpose of which is to condense the moisture as it leaves the 

 logs, in the form of hoar frost, on the principle of the dew pond. Thus the air 

 of the shed will be kept continually dry, and cold dry air constantly circulating 

 through and around the porous logs. He asserts that this would dry each 

 annual layer simultaneously, and that the shrinkage would be regular and 

 occur without cracking. Whether the proposed plant would really result in 

 the uniform curing of timber the reviewer must leave to the practical forester. 

 Perhaps the suggestion is much sounder on the practical side than the assump- 

 tions on which it is based would seem to indicate. — C. A. Shull. 



Philippine plant diseases. — Reinking* has published an excellent and 

 very useful account of the economic plant diseases of the Philippines, which 



'I Harrington, G. T., and Crocker, \Vm., Resistance of seeds to desiccation. 

 Jour. Agric. Research 14:525-532. 1918. 



5 Stone, Herbert, The ascent of the sap and the drying of timber. Quart. 

 Jour. Forestry 12:261-266. 1918. 



* Reinking, Otto A., Philippine economic plant diseases. Philipp. Jour. Sci. 

 13:165-274. pis. 20. figs. 43. 1918. 



