PERMEABILITY AND CLASSIFICATION 109 



fruits, seeds, and minute parasitic fungi. In my experiments 

 in those regions, I found it very difficult to dry the bared 

 kernels of seeds, or to dry seeds which had been cut across, 

 since mould used to form in a few days on the unprotected 

 or cut surfaces. 



But to return to the principal theme of this chapter, I 

 think enough has been said to connect with deficient shrinkage The connec- 

 the origin of permeable seeds in plants where impermeability permeability 

 is more or less the rule. Here, then, permeability is associated complete 

 with insufficient drying. Various allusions of similar signifi- shrinkage is 



. . , J , . . established 



cance occur in different parts or this work, and 1 have shown in this 

 that the trend of Professor Ewart's observations on the seeds cha P ter - 

 of the Australian Acacias is in the same direction. But clear 

 as the indications may seem, there has been another view of 

 the origin of impermeability during the seed's maturation 

 which has been advanced by Dr Gola. It is requisite to 

 remember that by an impermeable seed we always imply a 

 seed impervious to water ; and this will explain why mention 

 is not made in this connection of the recent researches of 

 Becquerel, which refer principally to imperviousness to air 

 produced by the desiccation of certain normally permeable 

 seeds, such as Peas, Beans, and Lupines (Annales des Sciences 

 Naturelles Botanique y 1907). 



Dr Gola's view, as stated not only in his original memoir, Dr Cola's 

 published in 1905 by the Royal Academy of Science of Turin, ne'ctinghn- 

 but also in the summary he himself contributed to the ^^^ llty 

 Botanisches Centralblatt in 1906, is that the impermeability maturity, 

 of its coats is due to the seed's insufficient maturation under 

 the influence of such climatic and local factors as cold, drought, 

 great humidity, excessive shade, etc. In order to show that 

 impermeability goes with immaturity, he gives in a table the 

 results of experiments on the seeds of seven species of 

 leguminous plants of the genera Acacia^ Cytisus, Genista^ 

 Robinia, and Trifolium, in which he connects the greater 

 tendency to absorb water with the greater maturity of the 

 seed. As given in Note 8 of the Appendix, where the table is 



