180 Alfred J. Ewart : 



placed in strong sulphuric acid often show the cuticle as a 

 separate layer before it dissolves away. In a few cases the 

 remaining integument may still delay the absorption of water, 

 but not in the remarkable way that thci cuticle does. In the 

 case of most plants producing hard seed, a certain variable 

 percentage of ea.ch sample will usually swell in water, and if 

 the seeds are not perfectly ripe this applies to all of them, 

 the cuticle being undeveloped or imperfectly developed. Such 

 seeds perish rapidly in the soil, but in ai dry herbarium may last 

 for many years, though rarely as long as the^ perfectly ri-pe 

 cuticularized ones, which swell only after breaking the cuticle 

 by filing or destroying it by sulphuric acid. The importance of 

 properly testing old hard seeds to obtain correct germination 

 values is well shown by the following experiment. One hundred 

 50-year-old seeds of each of 5 Leguminous plants were placed in 

 moist soil for 6 months in ai warm house, and kept under 

 optimal conditions for germination. None germinated, and with 

 the usual modes of testing the samples would have been con- 

 sidered useless. The remaining hard undecayed seed were," 

 however, taken up, the coats sand-papered, and the seeds placed 

 in germination chambers, with the following results : — - 



Acacia armata 

 ,, leprosa 

 Hardenbergia monophylla 

 Indigofera cytisoides 

 Watsonia viridifolia 



The Treatment of Hard Seeds. — Since this is a matter of 

 considerable practical importance, some detailed data are given 

 of the experiments made upon it with Acacia seed. 



The older idea that the impermeiilbility of the coats was due 

 to the presence of mineral maitter is quite incorrect, as is also 

 Jarzymowski's suggestion that it is connected with the small 

 size of the lumina in the palisade layer of the integument. As 

 Miss White has conclusively shown that the impermeability is 

 bound up with the presence of a cuticular layer over the seed, 



