NEW AND PARASITIC 



OF 



CHOANEPIIOEA 



BY 



1). 1). CUNNINGHAM, M.B., F.R.S., (I.E. 



In the early part of September 1894 my attention was directed, by a gentleman, 

 resident in Calcutta, to the presence of a destructive blight affecting plants of Jpm<ra 

 rubro-ccerufea, Hook, in his garden. Entire leaves or large portions of leaves and ax« 

 suddenly acquired a pale colour and presently wilted and died off, so that, during the 

 period when the blight was at its maximum, the growth of the plants was practically 

 brought to a standstill, the newly-developed leaves and shoots not doing more than 

 replacing the older ones which were constantly being killed off. 'I he extension of the 

 blight was greatly influenced by the character of the atmospheric conditions prevalent 

 at the time. During periods of continuous cloud and rain with maximal atmospheric 

 humidity it spread with great rapidity, whilst at times when sunshine prevailed and 

 the air was relatively dry its progress was very much slower. It continued to show 

 itself more or less conspicuously according to the state of the weather, during the whole 

 course of September and October, and then disappeared with the onset of cool and dry 

 weather in November. I was at first inclined to suppose that is was connected with tbo 

 presence of one of the various species of Sclerotica, or other closely allied fungi, 

 which occur so abundantly as blights during the latter part of the rainy season, hut 

 even very cursory examination was sufficient to show that this was not the case. 



On examining the affected parts before they had become dry and brown, the 

 surfaces could be seen to be clothed with numerous colourless, erect filaments with brown 

 dilated extremities (Plate VIII, Fig. 1), and these under the microscope revealed 



themselves as fructifying filaments emerging from the stomatic orifices and bearing 

 numerous brown conidia on capitula closely resembling those of Choanrphora Cunningham- 

 tana, Currey (Plate VIII, Fig. 2, Plate IX, Fig. 25). Both filaments and capitula were, 

 however, smaller than normal in that species, and the masses of conidia were of a pure 

 vandyke-brown colour and had not the purplish tint characteristic of those proper to it 



(Plate VIII, Figs. 2, 22, Plate IX, Fig. 25). . 



At this stage no mycelium whatever is present on the surface of the affected t,- ties 

 but at a later period and when numerous conidia have already fallen, the germinal 

 tubes, which rapidly emerge from these under favourable circumstances, may be present 

 m considerable numbers. The characters of the mycelium which is presen within the 

 tissues of the host-plant are essentially of a mucorine type. The most satisfactory demon- 

 stration of this is obtained in vertical longitudinal sections through the thickness of axes 

 as the course of individual filaments can be more readily traced in these than id 



Akn. Hoy. Dot. Gabd. Calcutta Vol. TI. 



