THE WHEAT CROP. 73 



the awns become twisted and curled, which readily in- 

 dicates the diseased ears (fig. 1). If one of the grains be 

 taken and carefully divided, the inside is found to be then 

 filled with a cotton-like substance, the original starch, &c., 

 having all undergone this curious change. In the centre 

 of this bed, an ordinary microscope will readily show you 

 a number of small eel-shaped animalcules twisting about 

 in all directions ; if placed in a little warm water, these 

 may be seen with the naked eye (fig. 5). The animalcule 

 causing this disease belongs to the order Infusoria, and the 

 significant name of Vibrio Tritici has been given to it, as, 

 so far as we know, it is met with only in the wheat plant. 1 

 The disease has been the subject of very interesting inves- 

 tigation by Raffredi, Henslow, Needham, and others, by 

 which it appears, that in the event of a sound grain being 

 sown by the side of an infected one, the young plant 

 grows up. all right until the spring, when the animalcules 

 find their way out of the diseased grain into the soil. 

 They then fix upon the young plant growing beside them 

 gradually ascend within the stem until they reach the 

 ovule there they form their nidus, deposit their eggs, and 

 die. Fortunately, the diseased grains are generally the 

 smallest and lightest in the ear, and thus -in the process 

 of dressing and winnowing they get separated, and are 

 less likely to be sown with the seed corn. 



The earliest injury the young wheat plant receives from 

 the insect tribe, is from some of the numerous family of 

 wireworms which are to be met with in all our fields, 

 and which attack indiscriminately well-nigh all our crops. 

 Wireworms are often confounded with the millipede, which 

 exist in equal numbers, though under different conditions. 

 The true wireworms are the offspring of the click-beetles 



1 So far as my own experience goes, it is far more commonly met with in 

 the coarser varieties of the T. turgidum, the rivet cone, and so-called Egyp- 

 tian wheats, than in the finer varieties of the T. sativwn. 



