THE SHRINKING AND SWELLING SEED 217 



communis and Hura crepitans. The seeds of the two plants just 

 named are permeable, whilst those of the leguminous seeds are 

 variable in this respect. If the kernels of the leguminous seeds 

 experimented upon were, as is probable in some cases, ultra- 

 dry, it would only be to a small degree (2 or 3 per cent.), 

 and not sufficient to materially affect their behaviour. For 

 practical purposes we may assume that the kernels of all these 

 seeds attain a more or less stable weight in the resting state. 



A singular feature of these dicotyledonous embryos, and 

 we may say the same of other similar embryos, such as those 

 of the sapotaceous genera, Achras and Chrysophyllum^ is that 

 they do not display in the resting seed the dried-up, shrivelled 

 appearance so characteristic of monocotyledonous embryos in 

 the naturally dried seeds of Palms, Cannas, etc. This is 

 probably due in part to the difference in form and situation of 

 the embryos in these two types of seeds. In the dicotyle- 

 donous seed the embryo lies flat between two slabs of albumen 

 and contracts with the kernel, leaving no unfilled space. With 

 ordinary seeds of Palms the embryo lies in an elongated cavity, 

 which it completely fills in the moist seed, but in the dry seed 

 it has shrunk away from the walls of the cavity. At all events 

 the water lost by the embryos of the moist seeds of both types 

 when drying spontaneously does not differ much in amount, 

 those of Palm seeds (Cocos, Areca, etc.) losing about 6G per 

 cent, of their weight, and those of the leguminous embryos 

 {Bauhinia, Cassia, Poinciana) 50 to 62 per cent. 



We have already dealt with the behaviour of the kernel Differentiat- 

 in the shrinking and swelling of seeds. Here, then, we are JhfbSiavlour 

 going to differentiate in the case of albuminous seeds between of the 

 the two components of the kernel, the embryo and the the albumen, 

 albumen. Allowing for the crudeness of the method, the 

 indications of the table below are clear enough. The embryo 

 and the albumen evidently go fairly well together in the three 

 conditions of the seed, and consequently in the shrinking and 

 swelling stages, each of them taking its proportionate share in 

 the processes. The deviations in opposite directions suffi- 



