224 HELMINTHOSPORIUM SPP. ON CEREALS AND SUGARCANE IN INDIA 
The above experiments furnish proof of the pathogenic nature of H. 
furcicum on maize leaves and inflorescence and show that the fungus on leaves 
and on the male inflorescence of tassel is identical. 
MORPHOLOGY OF THE PARASITE. 
Mycelium. The mycelium of the parasite ramifies in the tissues of the 
leaf and thus destroys the assimilatory apparatus of the plant, weakening 
tne plant so that its growth is checked. The spots in which the mycelium 
spreads later on become dry and brittle. The mycelium consists of branched 
septate hyphee, the cells of which sometimes become irregularly swollen. It is 
both intra- and inter-cellular. Inside the matrix the mycelium is subhyaline 
but where conidiophores arise it is light to olive brown colour. 
In culture a light greyish green colour appears which increases gradually, 
becoming darker. In old cultures the cells swell up, the cell wall becoming 
somewhat thick and thus give rise to thick-walled cells resembling chlamy- 
dospores. Spore formation takes place in cultures 6 or 7days old. Conidio- 
phores bear conidia at the apex. Sometimes conidia are formed with such 
rapidity that at the tip of conidiophore 3 or 4 are seen. These at first sight 
appear to be borne in cluster, but when observed carefully it is found that only 
the youngest is at the tip while the rest are just below in acropetal succession. 
Later on, as the conidiophores elongate, the distance between the spores 
increases and they become more and more lateral. The conidiophore becomes 
bent in several places where conidia are attached, but when spores are formed 
vigorously one after the other no such bending is noticed. Sometimes in 
culture no spore formation takes place, thisis especially the case when the 
fungus has been cultivated for a very long time in one kind of medium, but 
when the medium is changed, spores are formed again. On water culture or 
on the culture kept in a drop of water ina moist chamber abundant spore 
formation takes place. This method was employed to induce the fungus to 
form spores when it was sterile in culture tubes. 
The fungus loses its parasitic nature if cultivated for a long time in culture ; 
for instance, a fresh culture which was able to infect leaves vigorously was kept 
in culture for nearly a year, it was then used for inoculation but no infection 
took place. Fresh cultures which were exactly like the cultures of last year 
were again taken from the field and when inoculated gave successful results. 
Conidiophores are simple, septate and erect. They arise in clusters on either 
side of the leaf, are sometimes slightly bent above and are light brown in colour. 
They are 115 to 150 by 6to 87 indiameter and come out either through 
stomata or by directly piercing the epidermis (Plate I, figs. 18-21). 
