8o8 Journal of Agriculture. [lo Dec, 1910. 



A point of some interest is as regards the nature of the peculiarities 

 which serve to protect certain plants from the attacks of slugs and snails. 

 There can be no doubt that in many cases, it is a question of taste or 

 flavour, and this seems to hold good for widely dissimilar, vegetable-eat- 

 ing animals. For instance, fowls and well-fed cows usually refuse to 

 touch rhubarb, onions and bean-tops, and although cows will eat pea- 

 straw, they do not seem to be fond of it even when green. Even if they 

 are hungry, they do not appear to fill themselves with it in the same way 

 that they will with fresh grass or clover. All these plants disliked by 

 cows are also refused by slugs and .snails. The parallel does no<" how- 

 evei hold good in ^\\ cases. For instance, birds and stock generally will 

 eat sow thistle readily, whereas slugs and snails usually leave it untouched. 

 Tt mav be that when it is fully turgid and succulent, the slugs and snails 

 find som'^ difficulty in rasping through the stretched skin of the plant bv 

 means of their rough or saw-like tongues. It can. in fact, often be noticed, 

 narticularlv when pi anting nut yountr seedlings such as lettuces, cabbages, 

 &c., that the leaves are most rapidlv devoured when slightly drooping. 

 Apparently, it is when the tissues are loose and flaccid, that the snails 

 and slugs find it most easy to bore into them. 



In other cases, as for instance, in that of beet- root, it is difficult to 

 understand what protects the plants, anrl in anv case, the protection is only 

 a partial one .since the plants are not always immune to attack. Fowls 

 and cows will eat the leaves but do not appear to be as fond of them as 

 might be expected from their sutrar content. Tt has been suggested that 

 the red colour of the leaves of garden beet and other plants, bv simulating 

 blood colour, may act as a warning colouration, frightening away herbivorous 

 animals. Stahl. who first made this suggestion, remarked that the natives 

 in T'lvn often ^tow as hedf?e plants around their gardens, those with red 

 vegetation, and suggested that they may do this to frighten away various 

 large and small animals. As a matter of fact, the natives are fond of 

 bright colours, and a few thorns are more effective in keeping out large 

 animals than anv quantity of rfd foliage. Stahl tested his theory, as 

 regards the n-laticn between colour and taste, by feeding animals, includ- 

 ing slugs and snails, with slices of vegetables, .some of which were coloured 

 red 1)V carmine, and found \ery commonly that the uncoloured slices were 

 eaten first. This was. however, merely due to the fact that the colour 

 u.sed gave the coloured slices an unpleasant taste, and it is difficult to 

 see how any colour could possibly serve as a protection against slugs and 

 snails, which normally feed in darkness or in very feeble light where colour 

 is indistinguishable, at least to our eyes. 



It is evident that several interesting problems remain to be .solved in 

 regard to the psychology of slugs and snails, particularly in regard to 

 their sensations of taste and nalatability. Putting this on one side, how- 

 ever, there remains the fact that the use of sawdust soaked in phenyle 

 seems to be the most effective, cheapest and most permanent means of pre- 

 venting their ravages in gardens and in small plots under intense culture. 

 It does not kill them unless a strong solution is employed, but by keeping 

 them from their usual supplies of nutritious food, their numbers are soon 

 strictly limited, for animal pests only become so numerous as to I)e 

 troublesome, when they are provided with a safe, abundant and easily 

 accessible food supply. 



