1918} CURRENT LITERATURE 485 
In spite of this disagreement as to conclusions, however, GATES’s investi- 
gation is to be welcomed as being carefully made and as adding to our knowl- 
edge of the moisture relations of various plant communities.—Gro. D. FULLER. 
Germination.—LrsaceE* has made a rather extensive study of the effect of 
various conditions and reagents upon the germination of seeds of Lepidium 
sativum. He finds a selectively permeable membrane surrounding the seed, 
as has been found for many other seeds. This is shown by the fact that the 
yellow pigment of the seeds diffuses out when the integrity of the membrane is 
destroyed by mutilation of the seeds or by treating them with dilute potassium 
hydrate solutions. The exosmose of the hpigerets 6 ooputs wa Rydrate soupons 
considerably more dilute (#¢ mol.) than t 
(e's mol.). The data on the life duration of seeds. snaked i in various s concentra- 
tions of ethyl alcohol and aqueous solutions of salts followed by thorough 
washing in distilled water, are of great interest. Absolute alcohol did not 
injure these seeds after 4 years and 7 months soaking, and the life durations in 
various percentages are as follows: 
94 per cent....: 2... 2-3 months - aia cy ees .. 2 hours 
8 £6 re ae hours BF ge ed ie ae 4 days 
ce ae 20 hours eee re x6 days 
If these data are plotted into a curve with the duration on the ordinates 
and the concentrations on the abscissae, the upward face of the curve is concave. 
A similar relation between toxicity and concentration holds for several salts 
that were studied. For NaCl and KCI solutions the highest toxicity (shortest 
life duration in the solution) was in 1-2 mol., and for NH,Cl in 2-3 mol., higher 
concentrations proving less and less toxic as the concentration increased. For 
NaNO, the greatest toxicity lay between 2 and 4 mol., while for NH,NO,; it 
was between 1.25 and 6 mol. At the point of saturation, about 2 mol., KNO, 
had not reached its maximum toxicity. The seeds were not killed by 20 days’ 
soaking in pale concentration of N a.SO,, while es SO, showed its maximum 
toxicity at 2 m 
The seeds stil germinated after 4 years a 8 months soaking in petrol 
ether, but were quickly killed when soaked in ethyl ether. They germinated 
fairly well in moist air if it was saturated, but not at 98 per cent saturation. 
Temperature was an important factor here, 21° C. being the optimum. There 
is evidently a rest period in these seeds, for seeds one month old would not 
germinate in saturated atmosphere after 25 days, while 1-, 2-, 3-, 4-, and 5-year 
old seeds began to germinate after 3 days. Seeds that did not germinate after 
5 months in saturated air still retained their vitality. 
74 LESAGE, PreRRE, Au voisinage des limites de la germination dans les graines de 
Lepidium sativum. Rev. Gen. Bot. 29:97-112, 137-157, 181-192. 1917 
