MorpJiology. 1 5 



minutest portion applied to tlie tongue producing an 

 irritatino^ tino-linQ^ sensation that continues for some 

 time. This peculiar property appears to be due to 

 some chemical change in the latex caused by contact 

 with the air and probably with oxygen, as when a 

 drop is placed on the tongue, contact with air 

 intensifies the burning sensation, whereas if, after 

 rubbing the latex into the tongue, the part is covered 

 with oil or butter, no tingling sensation is felt on 

 exposure to the air. In other species the latex is per- 

 fectly mild, as in Lactarius pallidus. In most species 

 of Lactarius the latex is so copious that, when the 

 slightest wound is made, it flows out in considerable 

 quantities. In Russula, a genus closely allied to 

 Lactarius, laticiferous hyphee are also very abundant, 

 but the latex is denser and does not escape in the 

 liquid form when the tissue is broken, but the burn- 

 ing sensation produced when a minute portion of the 

 tissue is placed in contact with the tongue is in many 

 cases far more intense than in the genus Lactarius ; 

 liussida cut efra cta stands pre-eminent in this respect. 

 Bussula contains some of the most poisonous species 

 of fungi, but there is no necessary connection between 

 the pungency of the latex and the poisonous property; 

 Russula emetica is a deadly poison, but is mild to the 

 taste. Nothing satisfactory is known respecting the 

 functions of latex. For the purpose of studying the 

 laticiferous system, it is advisable to allow the speci- 

 men to dry for three or four days, as, if sections are 

 cut when fresh, especially in the genus Lactarius ^ the 

 whole of the latex escapes, whereas if it is allovv^ed to 

 dry, the watery portion of the latex evaporates, and the 



