THE BUn-ROT OF PALMS TN INDIA. 



2r)i 



Excepting the bundles and the bands of sclerencliyma, which 



are numerous, the par- 

 asite is found in all 

 parts of the leaf, reach- 

 ing to the bundle 

 sheaths on the one 

 hand and to the inner 

 walls of the epidermis 

 on the other. The 

 haustoria arise from 

 any part of the hypha^ 

 and are numerous. 

 They are found in 

 both parenchyma and 

 epidermis and are 

 straight or curved 

 finger-shaped pro- 

 cesses, which rarely 

 branch. 



Haioitoria of Pythhim pcdmlvorum. 



1. In tliiii walled parenchyma. '1. In an epidermal rell. 

 .S. did) and button-shaped hanstoiia with cellulose 

 cap. 4. Branched hanstoiiuin. 



After tlie internal mycelium has become copious and lias accu- 

 mulated a sufficient store of food from the contents of the host- 

 cells, branches from it emerge through the stomata to the surface. 

 When the next underlying sheath is closely in contact, it may be 

 infected by these hyphse without the formation of any visible super- 

 ficial mycehum. Often, however, there is sufficient space between 

 the sheaths (especially when the attacked area becomes depressed) 

 to allow of the formation of a considerable mass of wliite web-like 

 mycelium, which is one of the distinctive characters of the species. 

 No other species of Pythium known to me, nor any of the allied 

 genus Phytophthora, forms such a dense mycelium as the originator 

 of palm bud-rot. Under these hyphal masses it is common to find 

 hyphae emerging from the majority of the stomata. The superficial 

 hyphse differ but little from those within the leaf, except that they 

 are sometimes considerably thicker (plate IV, figs. 1 and 2). On 

 them and not on the internal mycehum, the reproductive organs 



