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 permeabTlity 



is more or less the rule. Here, then, permeability is associated ^"^^"gtg 



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



. established 



cance occur in different parts of this work, and I have shown in this 



that the trend of Professor Ewart's observations on the seeds *^ ^^^^'^' 



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, 1907). 



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



published in 1905 by the Royal Academy of Science of Turin, ^cting^in- 



but also in the summary he himself contributed to the J^thim^''**^ 



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 



