132 



PRIZE ESSAY : 



enter the roots and remain within the system of the plant until 

 such a change occurs in the process of its development that the 

 ovum of the future seed affords the appropriate nursery for its 

 growth. M. Bauer found the uredo foetida in the cavity of the 

 ovum before the ear emerged from its sheath, and the young 

 fungi in partial occupation. In this experiment the seed had 

 been purposely inoculated. 



236. The peculiar dark green colour of the infected grains is 

 a common effect of the presence of the mycelium of a fungus. 

 It stimulates the formation of the green colouring matter of 

 plants called the chlorophyle. Hence the rich tint of the so 

 called fairy rings, so often seen in pastures and on lawns, which 

 are produced by fungi. Dark green patches are occasionally 

 seen on leaves, and if the opposite under surface be examined, it 

 will probably be seen that a fungus has established itself there. (i) 



237. The investing coat of the spores is of an oily and sticky 

 nature, Avhereby they adhere to the substances with which they 

 may happen to come in contact. Hence in preparing seed the 

 use of alkalies or substances which will make soluble compounds 

 with the oily matter, or insoluble compounds destitute of adhesive 

 properties may be effectually employed to disinfect the grain 

 used for seed. The mode of steeping wheat noticed in paragraphs 

 232, 232(a), 231, will serve the necessary purpose. It is very 

 probable that a large proportion of the so-called smut of this 

 continent is nothing more than pepper-bread, and both are cer- 

 tainly common in our wheat fields. 



Ergota (Sclerotium chwiis.J — Ergot (Cocksjmr.) 



238. The exact nature of this curious substance is no longer 

 open to discussion. The observations of Dutrochet, Leveille, 

 and Quekett seemed to show that ergot is a disease of the grain 



(1) Berkeley, on the Potato disease. 



