WORMS. 221 



during the same year, the resulting malformation is 

 usually very considerable. "Clover sickness" is 

 probably due to this eelworm. 



I will treat in somewhat greater detail the Eelworm 

 Disease of rye, which is largely prevalent in West- 

 phalia and the Ehine provinces, and had already 

 made its appearance, in the latter at least, at the 

 beginning of the century. 



The eelworms producing the disease migrate into 

 the soil on the ripening or death of the grain, and 

 later on go back to the new young rye plants or to 

 other plants in which they can live, as the case may 

 be. It is therefore clear that (1) where this disease 

 exists the soil is infected for a time, and (2), the 

 eelworm disease of rye principally appears in regions 

 where the culture of rye is carried on to excess. 

 Germination of the seed-corn goes on quite normally 

 in infected fields, and it is only exceptionally that 

 anything particular is noticed in the young plants of 

 winter rye during autumn and winter. The disease 

 appears at the beginning of spring. Some plants 

 soon become yellow and die : others appear to grow 

 very luxuriantly; they possess a beautiful bluish- 

 green colour and seem very healthy; later on they 

 develop enormously in breadth, and each separate 

 plant covers a relatively large area. The base of the 

 stem swells abnormally, so that the plant looks as if 

 it bore below an onion projecting above the ground. 

 This is caused by the lower joints of the haulm 

 remaining very short and thickening considerably, 

 causing the leaf-sheaths which surround the base of 

 the stem to become thicker and broader than usual. 

 The feeble development of roots is also characteristic. 

 The leaves generally remain short, but get very thick ; 

 they often become wavy, and may even appear frilled. 

 All the leaves, however, are not crumpled in this way ; 

 a few remain quite normal, while others are small and 

 grass-like, but thick (Fig. 132). Later on, the tip of 



