HYGROSCOPICITY 157 



Later investigations on the desiccation of seeds have been 

 numerous ; but many of them are summed up by Becquerel Becquerel on 

 in his paper on the latent life of seeds (^Ann. Sci. JVat.y 1907). seeS^^^ 

 There are certain seeds, he points out, which are able to resist 

 the most powerful desiccating agencies at our command ; and 

 very significant is his conclusion, after a review of the liquid- 

 air results, that it is the seed where the water and " gaz " have 

 been reduced to the narrowest possible limits by the most active 

 desiccators of the laboratory that best withstands these tests. 

 There seems no necessity to assign a function to the extremely 

 minute amount of water that mi^ht survive the desiccating 

 process. 



On the contrary, it might be urged that its water is the Water is the 

 greatest foe to a seed's longevity. What, we may ask, is the fo'^l^eed's^ 

 real biological significance of the hygroscopicity of seeds, as ^°"ge^i^y- 

 far as their longevity is concerned ? It is their hygroscopicity 

 that limits the life of permeable seeds ; or, in other words, 

 the constant reaction between the seed and its atmospheric The hygro- 

 environment places a term to its existence. Not the least ticmiimfts^" 

 interesting of the conclusions drawn by Jodin from his ^^^dg^^^hilst 

 observations on peas lies in this direction, and we may apply its absence 



ui J • 1 T-u '• J u • favours their 



It to permeable seeds m general. The contmued hygroscopic longevity, 

 reaction, he points out, would in the course of time bring 

 about molecular changes in the seed, terminating in its loss of 

 germinative power and death. Thus we can perceive by 

 implication how the impermeable seed, by not responding to 

 the changes in its atmospheric surroundings, is secured against 

 one great risk to its longevity. Here, again, we perceive 

 that the long life of the seed presents itself as an affair of 

 the coats rather than one concerned with the dormancy 

 of the protoplasm of the embryo. It is the free play of 

 the hygroscopic reaction that curtails the life of a permeable 

 seed. It is the absence of this reaction that gives long life to 

 the impermeable seed. 



After this long digression on the significance of hygro- 

 scopicity in seeds, I come to my own studies in this connection. 



