110 



ON THE PROPAGATION OF BUNT. 



disease is not a mere alteration of structure in the grains of 

 fecula, were such testimony wanted. 



Four days after sowing I found that the spores of the Uredo 

 had been sucked in, doubtless by capillary attraction, between 

 the young root and its investing membrane, which was ruptured, 

 germination at that period having scarcely taken place. The 

 spores were quite as large as either of the two distinct series of 

 cells of which the young root is composed. 



Three days later I perceived the first traces of germination in 

 the spores. A little obtuse tube thicker than the pellucid border 

 of the spores, in a very few instances only, and appearing like a 

 short peduncle, scarcely so long as their diameter, was protruded 

 through the external membrane. This surprised me extremely, 

 because on the mass of spores, whether on the surface of the 

 soil or on the grains of wheat, there was a white, very delicate, 

 extremely short, down. On a closer examination the greater 

 part of the grains of bunt were found to be clothed on one side 

 with fascicles of white filaments, from two to four times longer 

 than the diameter of the bunt spores, and producing towards 

 their apices extremely long and slender, somewhat curved 

 acuminate multiseptate spores. 



Three days later a large portion of the grains of bunt were 

 ruptured, either irregularly or in a stellate form ; a few more 

 had germinated, the filaments being evidently protruded from 

 the internal membrane, and either straight or curved, and occa- 

 sionally branching off in two opposite directions, the tips of the 

 threads being in all cases very obtuse, and many times larger 

 than the intercellular cavities of the tissue of the roots. 



The parasite, meanwhile, had undergone a very curious change, 

 the spores being no longer separate, but connected with one 

 another by one or more short transverse tubes, exactly as in the 

 threads of Zygnema. 



Two days later many more of the bunt-spores were ruptured, 

 and the mycelium more elongated ; and, after three more days, 

 the parasite was vanishing, and scarcely visible any more " en 

 masse" to the naked eye, while the mycelium had increased to 

 the length of six or more diameters of the spores. The young 

 infected wheat-plants were now evidently diseased, the sheaths 

 and base of the leaves looking crumpled, and spotted either with 

 white or brownish specks, and the whole appearance less healthy 

 than that of the unimpregnated plants. 



The diseased sheaths were now, in most cases, full of mycelium, 

 but no such appearance was visible in the healthy state. Though 

 the disease had evidently commenced, it is to be observed that 

 the tubes protruded by the spores were but slightly developed, 

 and that, though the utmost pains were taken, I could trace no 



