EELWORM ‘‘ ONION-SICKNESS. ”’ MOE 
At p. 107 is a figure, not quite life size, of an infested Onion, 
photographed from a specimen grown in my own garden. If the 
reader will examine this with a magnifying-glass he will notice the 
unnatural thickening of the coats, and that these have gradually been 
pushed open and back until the edges of the quite outside scales are 
as much as a third of the width of the Onion apart, and those of the 
next inner ones half to three-quarters of an inch apart. 
In the figure given below, also taken from a photograph of an 
Eelworm-diseased bulb grown in my own garden, the same cracking 
and pressing off of the outer coats will be noticed, especially on the 
Eelworm-sick Onion, showing diseased growth. 
right side of the bulb, where four or five outer coats (the three upper- 
most dead and shrivelled) will be seen to have been pressed off by 
the much swelled development of the part of the bulb immediately 
beneath. 
The reason of this cracking open is given as follows by Dr. Ritzema 
Bos * in his admirable paper on this infestation :— 
‘* As in the case of this disease in Rye, the reason of the abnormal 
appearance of the plants similarly results from the fact that the 
growth in length of the fibro-vascular bundles is arrested by the 
presence of the Eelworms, whilst, on the contrary, the parenchyma 
of the leaves assumes abnormally enlarged proportions. From this 
it results that the plants remain short, swell, and shrivel”’ [or twist, 
* See ‘L’Anguillule de la Tige (Tylenchus devastatrix), et les maladies des 
plantes dues a ce nématode,’ par Dr. J. Ritzema Bos, I. p. 130, Haarlem. 
