JEHANGIR FARDUNJI DASTUR. 209 



oogonium at this stage was found to possess two walls ; the 

 internal contained only cellulose and no callose, or if at all 

 very little, and the external, on the contrary, contained chiefly 

 callose and little or no cellulose. In Ph. 'parasitica it is also 

 surrounded by two walls but the outer thick wall is not found to 

 be of callose. Congo red, 1 which stains both cellulose and callose, 

 failed to stain the oogonium, though hyphae, sporangia, " resting " 

 conidia and antheridia were stained. Cold strong sulphuric acid 

 had no action on it, even though the treatment was prolonged for 

 over a week, alkali carbonates and ammonia neither swelled it 

 nor gave it a gelatinous appearance, iodide reagents for cellulose 

 intensified its original yellow colour, it was not stained by nigrosin. 

 The outer thick wall of oogonia of Sclerospora graminicola has 

 been found by Mangin 2 to consist of pure callose and under the 

 influence of phosphoric acid this thick wall swells excessively, 

 becomes jelly-like and sets free the oospore, but the oogonial wall 

 of Ph. 'parasitica is not affected by this acid, even after a 

 long treatment. Malachite green, gentian violet, carbofuchsin 

 stain deeply all the parts of the fungus but the stain is washed 

 away by the use of acidulated water from all of them, except from the 

 oogonium. The same selective affinity for the oogonium is shown 

 by Hofmann's violet. Safranin, Kleinenberg's Hematoxylin, 

 Delafield's Hematoxylin and eosin do not stain the oogonium ; 

 iodide reagents for cellulose only intensify its yellow colour. These 

 chemical reactions and stains show that this thick outer wall is 

 composed of a chemical substance other than callose or cellulose. 



The possibility of this thick wall being composed of some pectic 

 compound substance was suggested by its staining beautifully red 

 with Ruthenium red, which has been successfully used by Mangin 3 

 for detecting the presence of compound pectic substances in the 



1 Mangin, L. Sur la callose, nouvelle substance f ondamentale existanl dans la membrane 

 dea cellules ties vegetaux. ('. R., C.\, 1890, p. 645. 



2 Ibid., Rechercb.es sur lea Paonosporees. Bull. Soc. d'Hist. Nat. d'Autun, VIII. 1895. 

 p. 97. 



3 Ibid., Sur L'emploi dn rouge de ruthenium ci\ Anatomic vegetale. ('. I'., CXVI, 

 1893, p. 653. 



3 



