44 JOSHUA ROSETT 



zontally in all directions, forming by their confluence a flattened 

 cup with an irregular, fringed border. I have called this type 

 of growth the floroid (see fig. 1, C). These horizontal tubes 

 are open above, where they do not come in contact with the 

 medium. In other words, the formation on the surface of the 

 medium consists of a number of convoluted and anastomosing 

 grooves and each groove is extended outward as one of the 

 branches. All three layers of the stem are represented. The 

 middle and outer layers are, however, much thicker than in 

 the stem, especially toward the center of the cup. In that situa- 

 tion the outer coats of neighboring canals coalesce, and the 

 appearance is that of a solid surface traversed by grooves (see 

 fig. 1, D). The diameter of the structure varies with the num- 

 ber of stems participating in its formation. A single stem may 

 produce a floroid as large as 2.5 cm. in diameter. 



When the upward-growing stem reaches the surface of the 

 solution near the wall of the vessel, it divides into two or more 

 branches, which proceed horizontally toward the wall, at which 

 point each branch bifurcates (see fig. 1, E and fig. 2, A and A')- 

 The new branches grow along the wall, in opposite directions, 

 at its junction with the surface of the liquid, until they meet 

 again at the opposite side of the vessel. The ring thus formed 

 continues to thicken until growth ceases. This ring-like growth 

 consists of a number of parallel canals situated at different levels, 

 and in cross section has the appearance of a honeycomb (see 

 fig. 2, B). I have called it the canalicular formation. 



While the stem is immersed in the medium, the surplus of 

 KMnO^ — that part not used up in the growth of the stem — es- 

 capes from the open tip of the stem, is partly reduced, is changed 

 in color to a red-brown solution, and rises to the top. "When 

 the stem has reached the top of the medium, however, this 

 surplus accumulates unchanged, either upon the flat cup of the 

 floroid or within the parallel canals of the annular formation. 

 The surface structure may therefore be removed from the vessel 

 and dried, after which it may again be placed in the solution, 

 with the result that new stems sprout forth from it and the whole 

 process is repeated. As the KMn04 is more protected from 



