62 CLOVER. 



or mould, but one chief cause is the presence of small eel- 

 worms in the stems and shoots. 



These eel-^Yorms {Tylenchm dcvastafrix, scientifically) are 

 too small to be observed without the help of a magnifier. At 

 full growth the males and females are about l-25th of an 

 inch in length, the exceeding slenderness of their eel-like 

 shape can hardly be conveyed by statement of measurement, 

 but when magnified 200 times, so that they appear a little 

 more than eight inches in length, their greatest magnified 

 width hardly exceeds one-quarter of an inch. They multiply 

 by laying eggs, and the eggs, young wormlets, and fully 

 formed males and females, may be found in great numbers in 

 the infested and misshaped stems and leaf-buds of the Clover. 



From the circumstance of the stems and shoots being 

 especially attacked by this Tylenchus the more serviceable 

 name of " Stem Eelworm" is given to this special kind, and 

 similarly the term Clover " Stem-sickness " is more useful for 

 describing this disease than the general description of " Sick- 

 ness " which includes all Clover ailments together. 



For practical purposes the deformed growth of the " Stem- 

 sick" Clover is quite sufficient to show the nature of the 

 attack, the amount of deformation of course may vary with 

 circumstances and season. 



Specimens sent from Woburn about the middle of April, 

 submitted to Dr. J. Eitzema Bos, Prof, at the State Agri- 

 cultural College, Wageningen, Netherlands, one of the highest 

 authorities on this attack, were reported on by him as 

 follows : — " The stalks and branches were shorter and thicker 

 than in the normal Clover jDlants ; the buds particularly were 

 much thicker, and some stalks and branches began to decay, 

 or were dying. I found in these plants larvas and adult 

 nematoid worms belonging doubtlessly to the species Tylen- 

 chus devastatrix. In the buds I found them in considerable 

 numbers." Early in July, in 1887, 1 had myself the opportunity 

 of examining excellently characteristic specimens of " Stem- 

 sick " Clover, also from Woburn. In this case some of the 

 stems with flowering heads were still to be found, but also 

 there were a large number of short barren shoots, about an 

 inch long, oval in shape, and with the distorted growth of 

 leaves then merely forming an imbricated, or "tile-like," 

 exterior. These shoots were placed closely together, ap- 

 parently from the growth of the shoot having been stopped. 

 They varied in number ; sometimes as many as five grew on 

 an inch length of shoot, one at the extremity and two at each 

 side below, so as to form together a flat, fan-like mass. I did 

 not find they grew round the central stem. They were not all 

 similar in form of diseased growth, but were commonly 



