284 



STRUCTURAL BOTANY 



builds up a network of hollow branched threads (the 

 capiUUium), which traverse the cavity in all directions 

 (see Fig. Ill, &). Between these threads masses of living 

 protoplasm remain. After the wall and capillitium are 

 completed, the formation of spores takes place. The 

 protoplasm in the meshes breaks up into distinct masses, 

 the nuclei of which all undergo division. It may be 

 mentioned here that the nuclear division in the sporangia 

 of Myxomycetes, and sometimes that in the plasmodium 

 as well, takes place in just the same 

 complicated way as in the tissues of 

 the higher animals and plants, al- 

 though, so far as the plasmodium is 

 concerned, it is probable that a 

 simpler process of division also goes 

 on. Ultimately the whole of the 

 living protoplasm in the sporangium 

 further divides up into spherical 

 spores, each of which includes a 

 single nucleus. 



The cell-wall of the spores, and 

 also the substance of the sporangial 

 wall and the capillitium, resemble 

 the cuticularised membrane of vegetable cells. In a few 

 cases cellulose has been found. It will be noticed that 

 complicated as the structure of the sporangia is, there is no 

 formation of distinct cells until the spores themselves 

 are developed. In Fig. 112 the sporangium of another 

 Myxomycete (Comatricha obtusata) is figured. Here the 

 sporangial wall soon disappears, so that the whole 

 capillitium in connection with the stalk becomes visible. 

 The sporangia of Badhamia open by the breaking 

 down of the membrane, and the spores are exposed. 



FIG. 112. Comatricha 

 oUusata. a, group of 

 sporangia. Natural 

 size, b, empty sporan- 

 gium, showing capil- 

 litium. Magnified 16. 

 (From Lister's Mono- 

 graph of the Myce- 

 tozoa.) 



