THE REST-PERIOD OF SEEDS 421 



after removal from the seed was long ago established by Van 

 Tieghem in the cases of Maize and Mirabilis (Nobbe, pp. 310, 

 31 1). Here, however, the resting seed was concerned ; and it 

 is more to the point to establish it for the embryo removed 

 from the seed before drying and shrinkage begin. 



I found that embryos of Iris Pseudacorus* removed from Detached 



r 11 i j embryos of 



their bed or albumen in the moist, uncontracted pre-restmg ins Pseuda- 



seed and then placed in water, increased their length in a few corus - 

 days from 4 to 7 millimetres and displayed the plumular 

 nob. The progressive growth of the embryo as the fruit 

 grows and matures is in this plant very evident. Whilst the 

 seed maintained much the same dimensions (7 millimetres), 

 I obtained the following results for the growth of the embryo 

 in different stages of the fruit's development : 



Immature fruit . . . embryo 1-5 mm. long 



Ripe fruit before dehiscence . 2 2'5 



Fruit beginning to dehisce . . 34 



With the object of inhibiting the rest-period and inducing Experiments 



, J , . , T i j inhibiting 



pre-restmg seeds to proceed at once with germination, 1 placed the rest- 



at different times a number of seeds of Iris Pseudacorus, Vicia peno * 

 septum, Arenaria peploides, and Quercus Robur under favouring 

 conditions in the moist, uncontracted state and obtained success- 

 ful results. Thus, after keeping some of the freshly gathered, 

 ripe, non-dehiscing fruits of the Iris in wet moss under warm 

 conditions (6o-7O F.) between ten and fourteen days, I found 

 that the drying of the fruits and seeds had been prevented and 

 that some of the seeds were germinating. The full-grown, 

 soft, uncontracted seeds taken from the green legumes of Vicia 

 septum behaved in the same way under the same conditions of 

 experiment. In four or five days they commenced to germinate, 

 and in five days the seedlings were half an inch long. The 

 white, soft seeds from the green capsules of Arenaria peploides 

 responded to my experiments precisely in the same fashion. 

 So also with Quercus Robur, it is not difficult to procure the 

 rapid germination of ripe acorns in September and October. 



