126 TECHNICAL BULLETIN 4. 



along the longitudinal walls, appear very straight. Thej' appear to pro- 

 gress somewhat more rapidly up and down the cotyledon than in a radial 

 direction inward. In the young stages they do not occur in strands or 

 bunches between the cells, but one finds them running singly (Figs. 4, A 

 and 5, D). They do not appear to be going toward any definite point, 

 but are spreading more or less in all directions. They are undoubtedly 

 septate, but the septa in the very j^oung hj^Dha; are difficult to distinguish. 

 The protoplasm passes to the growing tips, and leaves empty the cells 

 behind it. These tip cells stain deep \nolet with the triple stain, while 

 those cells behind them take less and less stain until onl}^ the thin line of 

 the walls can be seen. The nuclei stain bright red and are very prominent, 

 especially back of the deep violet tip cells. These nuclei may occur singly 

 or in pairs distributed along the hyphae. At this stage it is not always 

 possible to tell whether the two nuclei of a pair are in the same or different 

 cells, but bj^ a comparison with what is found in hyphse someAvhat older, 

 it is probable that here also the cells may be either uninucleate or bi- 

 nucleate. The contents of the hyphal cells appear homogeneous, and at 

 this stage there are no vacuoles or oil drops. The hyphs seem to be 

 mostly tightly pressed against the walls of the cells, but at places can be 

 seen passing from the wall of one cell to that of another across the open 

 spaces. The cells are long and the branching not close as in the later 

 stages. The branches always arise monopodialh^ from just below the 

 septum, as previously' described. 



Hmistoria. 

 These absorbing organs are not numerous, but are not uncommon. In 

 some infections none could be found, while in others the}^ are fairl}' com- 

 mon. They are of various sizes and of very irregular shape (Fig. 5, A-E). 

 They are not much different from the haustoria of other smuts as described 

 by various writers. They are always very much branched, but the 

 branches may be reduced to mere knobs or short stubs which are fre- 

 quently bifid at the apices (Fig. 5, A). In the larger haustoria, however, 

 the branches are longer and more lax, and may go to all parts of the cell 

 (Fig. 5, B and C). The branches of these larger haustoria are usually — 

 but not always — imbedded in the protoplasm about the nucleus. In 

 some cases they seem to be tightl^y gripping the nucleus, and the latter 

 appears indented by the pressure. Their shape and size can be best 

 understood by reference to the figures. In many of them an appressorium- 

 like expansion of the hypha can be seen flattened against the outside of 

 the cell wall, and from the lower side of this expansion a narrow neck 

 passes through the wall (Fig. 5, A, E). It is not certain, however, that 

 this apprcssorium is alwaj's present. In the larger haustoria, red nuclei 

 can be distinguished in varying numbers, but in smaller ones, and, in fact, 

 in man}' of the larger ones, no nuclei can be seen. In some, the position 

 of the nucleus in the stalk of the haustorium is evident (Fig. 5, C) but 



