CHAPTER V. COMPARATIVE REVIEW. HYMENOMYCETES. 



299 



defined than the strands of slender hyphae ; they are often much elongated in the 

 stipe and not unfrequently branched in the longitudinal direction or anastomose with 

 others. In transverse sections, especially in the stipe, the cells of many of the large- 

 celled portions are ovoid or wedge-shaped, and are so arranged, usually five or six 

 together, round a centre that their narrow ends converge towards it, and they thus 

 form a rosette on the transverse section. The cells thus arranged either form the 

 large-celled group by themselves, or they are surrounded by one or more irregularly 

 concentric layers of roundish cells ; other groups show two rosettes in the transverse 

 section, others again show no indication of arrangement in rosettes. The small 

 circular centre of the rosettes is formed by the transverse section of a narrow, 

 cylindrical, thin- walled hypha with limpid cell-contents, which runs longitudinally 

 and usually in a very winding course through the groups of large-celled tissue, as 

 appears in a longitudinal section. The laticiferous tubes which are characteristic of 

 Lactarius run through the strands of fine hyphal tissue, both close beside the large- 

 celled groups and at a distance from them, but without ever entering them. These 

 tubes have a large diameter as compared with that of the surrounding hyphae and a 



FIG. 136. Lactarius sitbdiilcis, Fr. Outer region of the stipe. < longitudinal section. * transverse section ; 

 o surface ; i laticiferous tubes. Magn. 90 times. 



very soft and extensible membrane, and they are filled to overflowing with a finely- 

 granular turbid latex which is differently coloured in the different species and oozes 

 out in large drops from the injured Fungus. The latex coagulates at the temperature 

 of boiling water and when treated with alcohol. It is therefore advisable in examining 

 the course of the tubes in sections to place the Fungi for a short time in alcohol ; in 

 order to make preparations through the isolated tubes, the parts of the Fungus should 

 be previously boiled a short time in water. Such a preparation shows that the tubes 

 send out numerous strong branches in every direction, which often form H-shaped 

 connections between two primary tubes, but never give rise, as far as I have observed, 

 to a net-work with narrow meshes. Here and there the stronger branches put out 

 short and delicate branchlets with very slender closed blind extremities. In older 

 specimens especially the laticiferous tubes are not unfrequently divided by single septa 

 placed at a considerable distance from one another. These organs traverse the hyphal 

 weft of the whole of the compound sporophore and their finer branches extend to close 

 beneath its surface. 



