166 VEGETABLE PAKASITES. 



representing, under the microscope, a mixture of mycelium, recep- 

 tacles, and spores, which show clearly the various steps of transi- 

 tion among themselves. 



1. The mycelium is formed of curved, bent, and simple cylindrical 

 tubes, forked or branched in all directions, with partition walls, which 

 are smooth and oblique, standing at unequal distances one from 

 the other. The tubes are strangulated and articulated, and have 

 an equal diameter of 0-003"' all along, and are bordered by a 

 smooth and pale edge. These tubes communicate most frequently 

 with those of the branches, sometimes they do not, and they are 

 then separated by a wall. The edges of the tubes are simple, 

 smooth, of dark colour, and their transparent surface without 

 granulation in the interior. Sometimes one end of the cavity is 

 seen free and floating, and the other adhering and communicating 

 with the granular stroma. A finely granulated mass is found 

 between the joints, and the sporidia are interspersed between the 

 thallus-threads. Robin denies the presence of joints and par- 

 tition walls in the latter. 



2. Receptacles or sporophora (the spore-tubes of some writers) 

 are tubes analogous to those of the mycelium, with short joints, 

 slightly contracted externally, cylindrical, usually less flexible and 

 brittle, so that they break up easily into single parts, empty in 

 one part, and provided in the other with small globules of 

 O001 2 mm., or with a single isolated corpuscle. Other 

 tubes, neither flexible nor branched, but straight or slightly 

 curved, contain similar, yet larger granules, of 0-004 5 mm., 

 which are, however, in closer proximity one to another, especially 

 towards the ends of the tubes, without ever touching entirely. 

 The last and broadest tubes, with occasionally occurring partition 

 walls, are denser (0*005 mm.) and longer and contain spores, which 

 are closely connected with one another. The tubes are 05 20 

 mm. long. There are also spores of 0-005 7 mm. in breadth, 

 and 0-007 11 mm. in length, provided with joints at certain 

 distances, and contracted at those places of juncture in which the 

 common envelope is no longer recognised. Sometimes, by a 

 division of the sporules, these rows are divided into two or three 

 smaller rows. It is uncertain whether these spore-tubes generate 

 in due time new ones, either at their origin or free end, as in other 

 cryptogams. 



3. The spores are generally round, spherical, oval, or irregular, 

 consistent, sometimes joined together and provided with smooth, 



