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way. These horns are highly sensitive to the touch, and shrink backwards when 

 tliey come in contact with anything that is in their road. If they had powers of 

 vision they would avoid touching the object before them, which they never seem 

 to do, but blunder head foremost into it. 



As to the shells of slugs, the Testacdla has its shell at tlie part of the body 

 farthest from the head, where it is attached in a very queer position, very much 

 as though it could not stay on, but must slip off. 



They, however, have shells which they carry within, as contrasted witli 

 outside, the creature itself. In some species they are very elementary, in others 

 they attain a fair size. They are formed of crystals of lime, I believe, and act as 

 protecting shields to the heart, lungs and very vital parts of the animal. On the 

 back of the slugs you will notice a fleshy growtli raised above the ordinary level of 

 the creature when crawling, and which, when it is at rest, acts as a protection to 

 the whole front part of the animal. Underneath this growth may be easily 

 obtained, by dissection, the shield which defends it from injury, and corresponds 

 to the shell of the snails. 



With regard to the threads of slugs and of fresh water shells. Let us speak 

 of the former first. Without a doubt some of them, but not all, have the power 

 of suspending themselves by means of a mucous thread which they excrete from 

 tlieir bodies, and which is sufficiently strong to enable them to lower themselves 

 from a height to a place not so lofty, say, for instance, the branch of a tree. This is 

 a good device when they are in search of fresh food, and saves a great deal of time 

 which otherwise would be spent in travelling to the trunk of the tree and then 

 journeying along another branch. As to the threads of fresh water shells, I am 

 unable to work out for you the question of the thread more than to record my 

 recollection that the snails do travel most elegantly and with great precision with 

 their heads downwards exactly at the level of the water in the aquarium. It has 

 been disputed whether there can be a thread, and as strongly asserted that there 

 is one. A microscope would settle the difference very soon. Tiie arguments 

 against the theory are that if a thread existed, it would be in the way of other 

 snails, and entangle them. I have no means of solving the question. Also, as to 

 the reasiming powers of snails. Have they any? Man, imperious man, says, 

 No, certainly not. We are lords of creation. None can compete with us. 

 Snails are very low in the scale of life. They cannot reason. Why then, 

 we ask, do they congregate in such numbers — Helix aspcrsa for instance — 

 in the cold time of winter as contrasted with warm weather? Why then 

 do they act sometimes with such rational powers as they do. Take an 

 instance. Several snails {Helix aspersa) were put into a box ; a thunderstorm 

 came ; the snails all escaped from the box. They were re-captured, and put again 

 in the box. Before long the cover was seen to move, and it moved regularly 

 backwards so that a small crack caused by the warping of the wood became so 

 wide that it was easy to see the creatures at work. There were several of them 

 and they pushed the lid further and further from its place by first gaining space 

 for their face, then their head, then their shoulders, until at last they were free. 

 Here were a number of them all working with the same object before them, all 



