286 



BOTANICAL GAZETTE 



[APRIL 



Conclusive determinations in regard to the reaction of fresh dry 

 seeds of Tilia have not been made, but preliminary tests, where 

 neutral red was used as an indicator, indicate that the endosperm 

 and cotyledons are acid and the hypocotyl alkaline. Seeds kept in 

 dry warm storage for 9 months show an acid reaction throughout. 

 Hydrogen ion determinations, the data for which are given 

 later, showed an acid reaction for the stored seed as well as for 

 the germinating ones. As germination begins, the reaction of 

 the embryo of Sambucus changes from alkaline to acid, but the 

 endosperm remains alkaline. Both dry and germinating Rubus 

 seeds are acid. A qualitative analysis of the ash of Tilia seeds 

 showed iron, calcium, magnesium, potassium, and aluminium 

 present. No tests were made for sodium. 



Experimental data 



Freshly harvested Tilia seeds with a moisture content of 10 

 per cent or less, or seeds kept in dry warm storage for several 

 months, fail to germinate when placed on a moist substratum and 

 kept at room temperature. This is true not only of seeds with coats 

 intact, but for those with the coats chipped or entirely removed. 

 Fungi and bacteria soon attack seeds with the coats broken and 

 decay takes place in a few days. The percentage of water held by 

 air-dry seeds is shown in table II. The seeds used for these deter- 

 minations were dried in a partial vacuum at 80° C. until the weight 

 was constant. 



TABLE II 



Water content of air-dry Tilia seeds 



* Average of 4 duplicates. 



The variations in the percentage of water lost by the seeds with 

 coats on is due to the presence of seed coats which contained no 

 endosperm and embryo. That the failure of air-dry Tilia seeds, 



