304 



BOTANICAL GAZETTE 



[APRIL 



inhibitory effect is shown by garden soil, clay, and greenhouse soil, 

 the effect of the last named being greatest. These soils acidified 

 gave no better results. Calcium carbonate used on filter paper or in 

 sand to neutrahze any acid present in the medium or remaining on 

 the seeds after the sulphuric acid treatment had no inhibitory 

 effect. Glass wool moistened with a boihng water extract or a cold 

 water extract of greenhouse soil cut down the percentage of germi- 

 nation to less than 50. Moreover, the seedHngs were weak, with 

 enlarged and discolored roots. In many cases germination started, 

 but the roots were killed as soon as they came in contact with the 

 substratum. Bone meal had been added to the greenhouse soil and 

 this probably accounts for the injurious effect of the soil and the 

 extracts. As is shown in table XIV, soaking in water for 24 hours 



TABLE XIV 



Effect of substratum upon germination of naked seeds of Riibiis Idaeiis; 

 100 seeds per culture; temperature 18-23° C. 



Substratum 



Filter paper 



Filter paper with CaC03 



Quartz sand 



Quartz sand 



Quartz sand with 5 per cent CaCOs . 



Greenhouse soil 



Greenhouse soil , 



Greenhouse soil, acid 



Hot water extract greenhouse soil. . , 

 Cold water extract greenhouse soil . , 



Garden soil 



Garden soil, acid 



Clay 



Percentage of germination after 



6 days 



SO 



31 

 48 

 42 

 43 



4 

 5 

 5 

 I 



8 days 



77 

 84 

 80 



83 



78 



22 



25 



25 



9 

 3 



I o days 1 2 days 



86 



87 

 83 

 88 

 80 

 10 



41 



48 



90 

 90 

 85 

 89 



13 



I 

 I 



29 

 10 

 II 



25 days 



95 

 92 



92 



93 



88 



25 



I 

 I 



43 

 48 

 29 

 10 

 19 



previous to planting in garden soil raises the percentage of germina- 

 tion to 55. On the other hand, soaked seeds planted on moist 

 cotton gave 71 per cent as against 72 per cent for unsoaked seeds. 

 Germination was at practically the same rate in the two cases. 

 Seeds planted on 5 per cent agar gave almost as high percentages 

 as those on i per cent. The results given in tables XIV and XV 

 show that the water supply is not the limiting factor. 



