212 SLUGS, FLUKES, EELWOEMS, ETC. 



marshes is well known, and is now shown to he due 

 to the poisonous action of the salt on the embryos, 

 sporo-cyst, redia, cercaria, and cyst, and to its similar 

 action on Limmeus truncatulus itself. Even a weak 

 solution of salt in water (containing only f per cent., 

 of salt) proves fatal to this Snail." 



This principle of prevention would be especially 

 applicable where (as in the instance, before mentioned, 

 in West Gloucestershire) it was the custom to have 

 exceedingly small ponds or cisterns of mason work 

 open to the field on one side, and very shallow, and 

 only a few yards square. From the immense quantity 

 of weed or grass growth in or at the edges of these so- 

 called "cattle drinks," and sometimes the quantity of 

 mud (which is stated to be the especial place of deposit 

 of spawn of the Limiucus tnincattilus), there was every 

 circumstance that was good for shelter, or propagation, 

 of either t)-inicatidus or jiereger ; and in circumstances, 

 like these a very small outlay on salt would carry de- 

 struction with it to the Snails and the Fluke embryos 

 in the water. 



Clearing the various vegetable trash, and sprinkling 

 some salt on the mud and into the water, would cost 

 little, and from the details given would, in many cases, 

 strike in embryo at infestation which presently, when 

 dispersed over the field, would be far more difficult to 

 deal with. 



Stem Eelworms {Tylcnchus devastatrix). — It has 

 only been in the course of the last few years that the 

 damage caused by the Tiilcnchus devastatrix, a minute 

 nematoid or thread-worm, which infests the tissues of 

 some crop plants, and of many common field weeds, 

 has been thoroughly brought under observation in this 

 country. Amongst the crops most observably infested 

 here are Oats and Clover; Wheat is sometimes 

 infested, and so are Beans ; Turnips are liable to 

 receive infestation when subjected to it experimentally,, 

 but not (so far as has been reported) as an evil practi- 

 cally. On the Continent, Eye is especially subject to 



