On the Differentiation of Tissues in Fungi. By G. Massee. 207 



anastomosing, as in L. torminosus ; the last type is most^ general. 

 The latex consists of exceedingly minute granules floating in liquid, 

 and is always colourless (white) when in the tissues, but on escaping 

 into the air frequently changes colour, becoming red in L. cleliciosus, 

 lilac in L. uvidus, and golden yellow in L. chrysorrheus. The colour is 

 due to some change taking place in the granular portion, the liquid 

 remaining colourless. 



The walls of the vessels are exceedingly thin in the species of 

 Laetarius, and liberate the latex or " milk " on the slightest touch. 



This tissue is undoubtedly connected with nutrition, or the trans- 

 portation of food-material, in the form of glycogen, which is considered 

 by Errera * to be of the same value in the nutrition of fungi as starch 

 is in chlorophyllose plants, and the reagents enumerated by this author 

 show that glycogen abounds in laticiferous vessels. In studying this 

 system, or testing for glycogen in species of Laetarius, it is advisable to 

 allow the plants to remain for a few days in a dry place, during which 

 time the more liquid portion of the latex evaporates, and sections can 

 then be cut without further loss of this substance, which in fresh plants 

 flows from the vessels at once, when injured ; neither is the reaction so 

 evident in fresh as in dried specimens. If sections from plants prepared 

 as above are sHghtly warmed in a solution of iodide (water, 45 grm. ; 

 potassic iodide, 0-3 grm.; iodine, 0-1 grm.) those parts containing 

 glycogen assume a dark orange or reddish-brown colour, depending on 

 the quantity present ; the colour becomes paler when heated to between 

 50°-60° C, and returns on cooling. In such preparations the laticiferous 

 vessels stand out as dark-brown lines. In the genus Bussula the liquid 

 portion of the latex is scanty, so that it does not flow from the vessels 

 when cut ; nevertheless the contents assume a dark reddish-brown colour 

 when treated with iodine as above, and in B. foetens Fr., by means of 

 this method of staining, I have satisfied myself by repeated observa- 

 tions that the cystidia met with in the hymenium of most, if not aU, 

 giU-bearing fungi are simply the terminal cells of laticiferous vessels. 

 These bodies, on account of their large size and peculiar properties, have 

 been the subject of much controversy and speculation : f by de Seynes % 

 considered as aborted basidia ; by others, as Corda, Hofimann,§ and more 

 recently by Worthington G. Smith, H as male reproductive organs ; hence 

 the names poUinaria and spermatia applied to them. Cystidia are very 

 numerous in the hymenium of some species of fungi, rare in others, and 

 in some perhaps altogether absent ; but in connection with this question 

 I cannot do better than give an extract from the article by W. Gr, 

 Smith abeady quoted : — " The receipt of the magnificent specimens of 

 Agaricus homhycinus from your correspondent the Eev. J. M. Du Port, 

 has again directed my attention to the subject of cystidia in agarics. 

 Knowing by experience how fine the cystidia are in some near allies of 



* Mem. Acad. K. Sci. Belg., xxxvii. (1885) and Bot. Zeit., xliv. (1886), 



t A. De Bary, " Morphologie und Physiologie der Pilze " in ' Hofmeister's Hand- 

 buch,' ii. (1886) cap. v. Translated in ' Grevillea,' i. (1873), p. 181. 



X ' Essai d'une Flore mycologique de la re'gion de Montpellier,' Paris, 1883. 



§ " Die PoUinarien und Spermatien von Agaricus," Bot. Ztg., xiv. (1856) pp. 137-48, 

 153-63. 



li ' Grevillea,' x. (1881), p. 77, and ' Gardeners' Chronicle,' Sept. 17, 1881, p. 360, 



