jehangir fardunji dastur. 205 



Composition of the Membranes. 

 According to Mangin 1 the mycelium of the PeronosporacecB can 

 be very easily distinguished from other fungi by the " constant 

 presence of callose, pure or associated with cellulose " which 

 partially or completely plugs the mycelial tubes at intervals. I 

 have failed to find this constant presence of callose in Ph. 

 parasitica. No doubt within the hyphse have been seen refrac- 

 tive, homogeneous, hyaline and generally bi-convex bodies which 

 completely fill the hyphal cavity (Plate V, Figs. 5a, c and d). 

 They arise as ingrowths from the inner walls of the hyphse (Plate V, 

 Figs. 1, 4d and 5). The hyphal cavity is closed either by one 

 such ingrowth extending from one wall to the other or by two 

 or more arising from the opposite sides and meeting at some point 

 within the hypha. These plugs, unlike the callose plugs found by 

 Mangin'" in the other Peronos'poracece, have never been observed 

 to originate as annular rings within the hyphse. They are com- 

 posed of pure cellulose and not of pure callose or callose associated 

 with cellulose. The presence of callose is indicated by a yellow 

 colour given to it by the iodine reagents for cellulose, e.g., 

 calcium chloride-iodide, iodine and phosphoric acid, iodine and 

 sulphuric acid and Schulze's solution. These reagents have in- 

 variably stained the plugs blue or violet without any trace of 

 yellow. Caustic soda and caustic potash easily dissolve callose ; 

 ammonia and alkali carbonates swell it and give it a gelatinous 

 appearance ; sulphuric acid slowly dissolves it ; cupric ammonium 

 hydrate has no action on it even after long treatment with strong 

 acids. These are the reactions given by Mangin 3 for callose. The 

 plugs found in our fungus are not dissolved by caustic soda or caustic 

 potash ; they are no way affected by ammonia and alkali carbonates, 

 they are readily dissolved by sulphuric acid ; after two hours' treat- 



1 Mangin, L. Sur la structure des Peronosporees. ('. R., CXI. 1890, p. 924 and Recherch.es 

 sur les Peronosporees. Bull. Soc. Hist. Nat. d'Autun, VIII, 1895, p. 76. 



2 Ibid. Sur la disarticulation des conidies chez les Peronosporii*. Hull. Soc. Bot. Fr., 

 XXXVIII, 1891, p. 234. 



3 Ibid. Sur la callose, nouvelle substance fundamental*' existanl dans la membrane des 

 cellules des vegetaux. C. R., CX, 1890, p. 64G. 



