HYGROSCOPICITY 179 



is made to the results of experiments made by Nobbe, Jodin, and the 

 author in this connection ; and it is established that the normal 

 hygroscopic reaction cannot provoke germination, the minimum 

 amount of water required for germination being far in excess of that 

 which a seed would take up unaided from the air (p. 171). 



(18) The nature of the extreme limit of a seed's hygroscopicity 

 is then discussed ; and the author, after laying stress on the especial 

 risks of mould and condensation to which such experiments are 

 liable, follows the indications of his own experiments in accepting 

 a range in weight of 5 or 6 per cent, of the average weight of the 

 seed as the greatest amplitude of normal hygroscopic variation, the 

 usual range, however, being only 2 or 3 per cent. Hoffmann's 

 results point in the same direction, and precisely the same limits 

 to the hygroscopic range of weight are established by the author's 

 observations on the weight of dry pods (p. 172). 



(19) The results of these observations on air-dried legumes are 

 then tabulated, and it is shown that leguminous pods with permeable 

 seeds display much the same degree of hygroscopicity as their seeds, 

 the pod being hygroscopic whether the seeds are permeable or 

 impermeable (p. 174). 



(20) Although the ordinary maximum of the normal hygroscopic 

 range has been above stated, the author regards the possible extremes 

 of a seed's hygroscopicity as outside the present inquiry. 



