TILLETIA TRITICI 275 



The Phenomenon of Protoplasmic Migration. — The advance of 

 the protoplasm in a hypha toward the apical growing point and its 

 basal delimitation by the formation of cross-walls is a phenomenon 

 which is well known to occur in various fungi. Thus Buller 1 has 

 described it in connexion with the development of the germ-tubes 

 of Polyporus squamosus. However, up to the present, the conditions 

 under which a new septum is formed do not seem to have been 

 determined. In what follows an attempt will be made to throw 

 some light on this problem. 



Protoplasmic migration with the formation of septa occurs in 

 Tilletia tritici in the promycelium, the sterigmata, the basidiospores, 

 and in the mycelium arising either from an H -shaped pair of 

 sterigmata or from a basidiospore (Fig. 114, A, B, and Fig. 130, 

 A, B, C ; pp. 232 and 260), so that it is a phenomenon of considerable 

 importance in this fungus. It has been studied more especially in 

 promycelia. 



Some chlamydospores were germinated on the surface of sterile 

 distilled water contained in a Syracuse watch-glass. Many of the 

 promycelia grew along the surface of the water. As they elongated, 

 their protoplasm migrated toward their apices, and in various 

 promycelia all stages of protoplasmic migration and of septum- 

 formation could be observed. A series of stages leading to the 

 formation of a new and empty cell was followed in a single promy- 

 celium and is illustrated in Fig. 135. 



In Fig. 135, A, is shown a chlamydospore cl from which had 

 grown out a promycelium which now consists of three cells — two 

 clear basal cells, a and b, and a long terminal apical cell, t. The 

 basal cells have lost their protoplasmic contents and therefore are 

 dead and contracted laterally ; while the apical cell is filled with 

 protoplasm, is living and fully turgid, and is therefore uncontracted 

 laterally. The two septa s' and s" are concavo-convex, the con- 

 cavities being directed toward the apex of the promycelium. The 

 septum 8" separates the dead cell b from the living terminal cell t. 



In Fig. 135, J, is shown the same promycelium as in A, but 3-4 

 hours later. J differs from A in having a longer promycelium and 



1 A. H. R. Buller, " The Biology of Polyporus squamosus, a Timber-destroying 

 Fungus," Journ. Econom. Biol, Vol. I, 1906, pp. 119-120. 



