568 TRANSACTIONS AND PROCEEDINGS OF THE [Sicss. i.vir. 



colour than the rest of the seed-coat ; the double character 

 of this elevation is easily made out by means of a hand 

 lens, the two tubercules being somewhat darker in colour 

 than the median line which divides them. 



Germination. — As soon as the seed is placed in damp 

 soil, it commences to swell, owing to the absorption of water 

 in considerable quantities, through the whole surface of the 

 seed-coat, but specially through the hilum. The time 

 required for complete saturation varies in difterent species, 

 and also in different individuals of the same species, though, 

 in the latter case, the great majority of the seeds contained 

 in any one sample will become saturated in about the same 

 time. 



Detnier (iii.) found that out of 1000 seeds of Trifolium 

 irratense placed in water, 919 were completely saturated in 

 one day, while at the end of ten days only 25 more were 

 fully swollen, and after 15G days 30 seeds in one ex- 

 periment and 10 in another remained still unaffected. 

 According to the observations of Bruying (ii.), a still larger 

 percentage of the seeds remain hard in the case of Ulcx 

 curoiKcuH. In this plant only 4-7 per cent, had germinated 

 after six days, while at the end of fourteen days 30'2 per 

 cent, showed signs of growth, leaving a very large percentage 

 of " hard " seeds. 



A^'arious methods, having for their object the obtaining 

 of a higher germination percentage, were tried by this 

 author — the seeds were treated with sulpliuric acid of 

 various strengths, with solutions of soda, etc., but the best 

 results were obtained by mechanical abrasion of the seed 

 coat by means of sharp sand ; seed so treated gave a 

 germination percentage of 30'2 after six days, and of 63'5 

 after fourteen days. 



As soon as suHicieiit water has l)een absorbed growth 

 commences in the embryo, and this, aided l)y the swelling 

 of the inner layers immediately around the embryo, 

 "Schleim endosperm," causes the rupture of the hard 

 outer wall. As the radicle is the i)art in which growth 

 first appears, it is usually in its neighbourhood that the 

 seed-coat splits, and in most cases the split, commencing 

 near the tip of tin; radicle, extends transversely on each 

 side of it, passing round the sides of the seed. 



