302 



BOTANICAL GAZETTE 



[APRIL 



and finally rinsed in running water for 15 or 20 minutes. The 

 carbonized endocarp was removed by rubbing the treated seed on 

 filter paper. The selection of perfect seeds was now an easy matter. 

 Table XII shows that the water-absorbing power for the seeds 

 with the endocarp removed is 36-37 per cent of their air-dry 

 weight, while that for the seeds with the endocarp intact reaches 



TABLE XII 

 Water content and water holding capacity of Rubus seeds 



Condition of seeds 



Endocarp removed 

 Endocarp removed 

 Endocarp intact. . . 

 Endocarp intact. . . 



Weight of 



air-dry seeds 



in gm. 



0.6686 

 0.6864 

 I . 0464 

 2 . 0960 



Weight of 

 seeds dried 

 in vacuum 



at7S°C. 



0.5842 

 o . 600Q 



0.9328 

 1.8680 



Percentage 



of water 



in air-dried 



seeds 



12.62* 



12.45 

 10.85 

 10.87 



Weight of 



soaked seeds 



in gm. 



0.9120 

 0.9414 

 I 5053 

 3 



.0080 



Water Percentage 

 absorbed byi of water 

 air-dry seeds absorbed by 



in gm. air-dry seeds 



0.2434 

 0-2550 

 0.4589 

 0.9120 



36.40* 

 37-15 

 43-85 

 43-51 



* On basis of air-dry weight. 



almost 44 per cent of their air-dry weight. From this it follows 

 that the water absorbing power of the endocarp is greater than that 

 of the seed with the endocarp removed. There is no evidence to 

 show that the endocarp possesses any structure which would 

 prevent the water absorbed by it from being passed on to the seed. 

 Although seeds with the 'endocarp intact will not germinate, when 

 that structure is removed by means of the sulphuric acid treat- 

 ment germination takes place within a few days, as is shown in 

 table XIII. 



The greater amount of the germination takes place between the 

 fourth and tenth days. In seeds germinating after the tenth or 

 twelfth day, growth is usually slow and the seedlings are weak. 

 Failure to secure 100 per cent germination is due to the fact that 

 during the removal of the carbonized endocarp in almost every case 

 the seed coat is ruptured and the endosperm exposed to the attacks 

 of bacteria and fungi. With the carbonized endocarp intact, 

 uncertainty as to the extent to which the acid had penetrated and 

 the inabihty to determine the number of fruits containing viable 

 embryos lead to greater error than that occasioned by the attacks 

 of the bacteria and fungi. 



