34 British Vegetable Galls 



II. The Angullula, or Eel-worms. 



The minute nematoid worms popularly known as Eel-worms 

 are very destructive to many kinds of plants, more especially 

 cereals. Their name is indicative of their shape which under 

 magnification is seen to bear a very close resemblance to an eel. 

 They are very small, thin-skinned, and live in enormous numbers. 

 About six species produce galls. 



The ova of these creatures are relatively large ; the larvas 

 quickly develop from them, and at once commence to suck 

 the sap from young roots and to bore into them. When fully 

 grown they are not quite i mm. long. They attack the roots 

 and other parts of wheat, rye, oats, clover, parsnips, beet, 

 lettuces, tomatoes, cucumbers, and peach-, pear-, and walnut- 

 trees. Several wild plants are also affected, Poa annua, 

 Achillea viillifolium, and Polygonum persicaria amongst them. 



The mouth is furnished with an exertile, sharply pointed 

 spine, which is employed to penetrate the tissues of the plants. 

 They bore into and live within the plant, producing galled 

 growths, and considerably retard its development. 



The generations succeed each other very rapidly. About 

 thirty days only is necessar)- from the emersion of the embryo 

 from the egg to the mature se.xual adult form. 



Kuhn's investigations have supplied many details concerning 

 the species Heterodera scluiclitii, which affects the beetroot. 

 The ? may be found attached to the rootlets of the beet. At a 

 certain stage of growth she becomes distended into the shape of 

 a lemon, which causes her death. The skin is then a mere sac, 

 which may contain as many as 400 ova. The larvae emerge 

 from the majority of these within the sac, but, owing to the 

 pressure from within, it ultimately ruptures, and the larvae are 

 liberated ; they at once commence to attack the rootlets around 

 them, and cause the formation of gall-growths. 



III. The Coleoptera, or Beetles. 



The galls caused by beetles are known as Coleopterous Galls. 

 It is very remarkable that among all the British beetles, which 

 number about 3,300 species, only about fourteen cause gall- 

 formations in the plants upon which the larva; feed. Probably 



