134 



gradually more transparent and finally 'melt away.' ' In Colletotrichum 

 Gardner (58) found the fungus similarly seeking the "depressions bounding 

 the epidermal cells." This place of entrance is characteristic of many fun- 

 gisee Biisgen (30), Rehrens (15), Ward (123), Noack (ST^Miyoshi (83), 

 Nordhausen (88), Schellenberg (99), and Aderhold (1). The last three 

 named, believe this to be due to chemotaxic influences. Noack in describ- 

 ing the entrance of H. gramineum into the host mentions the appressoria. 

 Similar structures have also been described in the anthracnose fungi by 

 Hasselbring (64) and by Gardner (58), the pore in these structures being 

 such as I find in Helminthosporium, though the appressorium in the anthrac- 

 nose fungi is a mere swelling and is hyaline. Similar extreme narrowness 

 of the mycelium at the actual point of penetration of host-walls is shown 



FIG. 22. H. Xo. 14 on wheat, showing fan-like mode of branching, see p. 105. 



also by Ward (123, fig. 57), Gardner (58, page 27), Hasselbring (64*, 

 Biisgen (30), and Noack (87). Bakke (6) says of H. teres that the 

 mycelium "penetrated the epidermis directly and made its way through 

 the intercellular spaces," but he gives no further details. 



Conditions very closely resembling the "callus" formation are figured 

 by Dastur (41. figs. 8, 9); depicting the entrance of smut into sugar- 

 cane. This appears to have occurred only occasionally, and Dastur re- 

 gards the "callus" ("plug") as probably a means of preventing infection. 

 Conditions somewhat resembling that of the "callus" formation are de- 

 scribed and figured by Wolff (128, figs. 2, 3) and by Brefeld (25, fig. 2) 

 in the penetration of smuts into cereal tissue. Wolff (128, p. 20) de- 

 scribing this says: "Es tritt hierbei der eigenthiimliche Umstand ein, 



