1908] Botanical Branch. 103 



ment when growth is resumed. It is stated or suggested by 

 some botanists of repute that this so-called non-maturity of the 

 embryo in sound and apparently ripe seeds is the cause of de- 

 layed germination of most seeds that seem to require a rest 

 period. Some recent work by Crocker, however, would seem to 

 disprove this theory with many, but not all, kinds of seeds. 

 The hawthorn, for instance, will germinate very sparingly 

 during the first two years, even though ideal conditions for growth 

 be provided, by artificial or other means. 



(b). Water content. The ideal condition for preserving 

 life and vital energy within the embryo of most seeds is storage 

 in a relatively cool, dry place. Even under the best conditions 

 of storage, seeds gradually part with their moisture content. 

 The rapidity wath which this takes place is believed to be due 

 largely to the condition of the seed coat. If the seed coat be 

 such as to hermetically seal the embryo with its food supply, 

 then life is preserved, under proper conditions of storage, for 

 a longer period. 



Germination of the seed or resumption of growth on the 

 part of the embryo can not take place unless the embryo is able 

 to secure a sufficient supply of water, even though the embryo 

 may be fully matured and ready to commence growth. Crocker 

 found that in most kinds of seeds, such as are to be found among 

 the cruciferae, borraginaceae, the plantains, the iris, and many 

 species of water plants, that the embryo and its store of food 

 was so completelv sealed in a seed coat, impervious to water, 

 that germination could not take place. He conducted extensive 

 experiments wilr £eed^ of various kinds of plants by germinating 

 them at dift'erent temperatures, with some of which seeds he 

 artificially striated, or clipped the seed-coat, in a way not to 

 injure the embryo, and compared the germination with seeds of 

 the same kind on which the seed coat remained intact. With 

 very few exceptions he found that the artificial clipping of 

 freshly-ripened seeds (by which process of clipping he enabled 

 the water to reach the embryo) induced prompt growth, 

 whereas those with seed coats not clipped failed to germinate 

 or germinated very sparingly; further, that the various kinds of 

 seeds differ in respect to the temperature best suited to the re- 

 resumption of rapid growth on the part of the embryo. It 

 was found that w'ith some of the seeds that were not entirely 

 impervious to water but in which inhibition took place slowly, 

 that the embryo swelled and filled the cavity occupied by it, 

 and yet growth did not commence. As soon, however, as the 

 "plug", or that small portion of the seed coat of some species 

 of seeds (iris) which is contiguous to the embryo, was removed, 

 artificial growth at once commenced. Crocker's work entirely 



