a6o 



LECTURE XV. 



conveyed to them by the rain. These materials (chiefly potash, ammonia, phos- 

 phoric acid, and the less important silica) are found in the soil in a peculiar 

 combined condition: they are, as we are accustomed to say, absorbed. An 



Flo. 206. FIG. 207. 



Fig. ojS. Seedling of Wheat plant. Fig. 207. Tile same four weeks older, i- the seed coats. &c i 71/ the apices 

 of roots not yet furnished with hairs ; e parts attached to the soil (in Fig. zo6). In Fig. 207 the hairs are already 

 perished on these parts, e' younger parts of roots attached to soil. 



illustration of this fact^ is obtained most easily by filling an ordinary funnel 



1 On the absorption and taking up of absorbed matters, a very thorough account is found in 

 my ' Handbuch der Experimental-physiologie,' l86,s, p. 178. The corresponding section in Pfeffer's 

 ' Pflamen-physiologie'' (i88i) shows that essentially nothing new is to be added concerning the 

 subjects mentioned in the previous and following notes. 



