1 68 



LECTURE X. 



and waste-products, such as resins and caoutchouc, which form an emul- 

 sion. It has been observed in some cases that the latex coagulates spon- 

 taneously. 



Weiss and Wiesner found the following substances in the latex of 

 Euphorbia platyphyllos : 



Undissolved proteid and starch 2*02 per cent. 



Dissolved proteid and carbohydrate 0*51 



Fat i'33 



Sugar and extractives 6^41 



Gum 2*15 



Resin 8*12 



Ash 1-51 



The statements made above as to the tissues in which 

 organic substances travel from one part of the plant to another 



FIG. 25 (after Sachs). A twig which had been kept standing in water after the 

 removal of a ring of cortical tissue. N, level of the water : P, swelling formed 

 at the upper margin of the annulation : W roots. 



