STEM EELWORMS. i 45 
The first enquiries which I received during the past season 
regarding what proved to be Clover ‘“‘ Stem-sickness’’ were sent me 
on March 25th by Mr. Martin J. Sutton, from Kidmore Grange, 
Caversham, on the part of a correspondent near Sawbridgeworth, who 
had applied to him for information regarding ‘“‘ the cause of failures of 
Clover this year.” The details were as follows :— 
On April 20th last year’’ [1895] ‘‘I drilled ten pounds of best 
Giant Hybrid Cow Clover in a field of thirty acres amongst a strong 
plant of Wheat. The preceding crop was a heavy one of Trifolium 
incarnatum. Neither the Trifolium nor Wheat had any manure. The 
land for Wheat was twice steam-cultivated. The Clover stood the 
drought of last spring well; and after the Wheat was harvested the 
Clover appeared vigorous, and continued to do so until Christmas, 
since which time it has gradually died off, so that now there appears 
not to be half a crop left. 
‘Ags the winter was mild, it cannot be attributed to frost, and 
there is no insect at work. The land contains plenty of lime and 
potash, and the field has not had Clover since 1884. The soil is a 
good clay loam, and is well drained with pipes. The Wheat crop was 
a good one, over five quarters per acre. . . . I may mention that 
I have heard of many cases of failure in this neighbourhood.” —(Per 
favour of Mr. M. J. Sutton.) 
The specimens forwarded were characteristic examples of Clover 
‘“« Stem-sickness,”’ caused by T'ylenchus devastatrix, or Stem EKelworm. 
The shoots were much stunted and distorted in growth; the terminal 
bud flattened and swelled, and the rest of the shoot much beset with 
scales. As many as about a dozen deformed shoots, ranging from 
three-quarters of an inch or less in length up to about an inch and a 
half, were to be found, making a kind of crown to the roots; and 
within I found the Eelworms, some full-grown, and others of various 
sizes, ranging down to about a quarter of the full size. 
The Helworms, Tylenchus devastatriv scientifically, are just like 
very minute eels, of the shape figured at p. 44, and still more magnified 
on the Plate, showing specimens taken from infested Onions, accom- 
panying the paper on ‘‘Onion-sickness.” They are of exceedingly 
small size, namely of only one-twenty-fifth of an inch in length, and 
one-thirty-second part of their length in width. They belong to the 
division of the Nematodes, or Threadworms; and the Tylenchi are to 
some degree distinguishable by having within the gullet, or cesophagus, 
a long process called a spear, placed on a three-lobed base (see figures, 
p. 44); they multiply by eggs; and the eggs, wormlets, or larva, 
and the males and females, may often be found together in infested 
plants,—it may be in parts of the diseased growths or swollen leaf- 
buds (in the case of Clover), or very frequently in the brown or 
