iqiq] rose— AFTER-RIPENING AND GERMINATION 297 



and N/400; of the bases, N/iooo, N/2500, N/5000, and N/io,ooo; 

 and of the salts, N/20 and N/2do. The number of perfect seeds in 

 the cultures varied from 43 to 96. In only 4 cases was the number 

 below 60, and the average was 75. This variation is due to the 

 presence of empty seed coats which could not be distinguished from 

 the perfect seeds until they had taken up a considerable quantity 

 of water. It was later found possible to candle the seeds and thus 

 eliminate the majority of the empty coats. The candling was done 

 by means of an incandescent light supported below a glass plate 

 upon which the seeds were placed. Between the light and the plate 

 was placed a vessel of water to prevent undue heating. The seeds 

 were placed in 20 cc. test tubes containing the solutions and allowed 

 to soak for 24 hours. At the end of that time the solutions were 

 drawn off and the seeds distributed over the moist walls of the test 

 tubes, which were then plugged with cotton and kept at a tempera- 

 ture varying from 4 to 23° C. As soon as the seeds began to show 

 signs of germination, they were removed from the tubes and placed 

 in Petri dishes on moist cotton and kept at room temperature. 

 Germination was slow, in the majority of cases extending over a 

 period of 3 months. In the case of acetic acid, N/400, 58 per cent 

 of the seeds germinated at the end of 176 days. The acids other 

 than acetic showed Httle effect. The length of time over which 

 bases can have any effect must be short, since in dilute solutions 

 they are sooii neutralized by the carbon dioxide of the air and that 

 produced by the seeds. The cultures which showed germinations 

 equal to or better than the checks are Hsted in table X. 



In order to test the effect of constant low temperature upon 

 seeds soaked in solution of various chemicals, a second set of 

 cultures was prepared in the manner already described and kept at 

 4-6° C. for 63 days. At the end of that time the tubes were placed 

 at room temperature. To the list of substances used in the pre- 

 ceding experiment were added potassium citrate, potassium tar- 

 trate, potassium acetate, potassium chlorate, ammonium nitrate, 

 potassium iodide, lithium chloride, ammonium chloride, magnesium 

 chloride, sodium nitrite, and dipotassium phosphate, and also 

 hydrochloric acid and sulphuric acid. The concentrations of the 

 mineral acids were N/iooo, N/2500, N/5000, N/io,ooo, and of the 



