222 RESEARCHES ON FUNGI 



locomotion in response to the chemical stimulus arising from 

 the odoriferous substances which the fungi give off. 



Previous Chemotactic Experiments. As evidence that slugs 

 find their food by their sense of smell A. H. Cooke cites the following 

 observations * : 



" M. Parenteau was one day walking along a dusty high-road, 

 when he noticed, near the middle of the road, an empty bean-pod 

 and two Arions eating it. Attributing the meeting of feeders and 

 food to mere chance, he was walking on when he noticed a second 

 bean-pod, and, about two yards away from it, a third Arion, hurry- 

 ing straight towards it. When the Arion had yet more than a 

 yard to traverse, M. Parenteau picked up the bean and put it 

 in his pocket. The Arion stopped, raised its head, and turned in 

 every direction, waving its tentacles, but without advancing. 

 M. Parenteau then carried the bean to the other side of the road, 

 and put it in a small hole behind a piece of stone. The Arion, after 

 a moment's indecision, started off straight for the bean. Again 

 the position of the precious morsel was changed, and again the Arion 

 made for it, this time without being further tantalised. 



" M. Moquin-Tandon noticed, one rainy day in the botanical 

 gardens at Toulouse, two Limax maximus approaching a rotten 

 apple from different directions. He changed the position of the 

 apple several times, placing it at a sufficient distance to be sure they 

 could not see it, but they always hit it off correctly, after raising 

 their heads and moving their long tentacles in every direction. 

 It then occurred to him to hold the apple in the air, some centi- 

 metres above the head of the Limax. They perceived where it 

 was, raised their heads and lengthened their necks, endeavouring 

 to find some solid body on which to climb to their food." 



As confirming M. Moquin-Tandon's experiment, and as further 

 evidence that the olfactory sense in Limaces is extremely acute, 

 J. W. Taylor in his Monograph relates the following 2 : 



" Mr. L. E. Adams, about ten o'clock, one dark, windy, and 



1 A. H. Cooke, Cambridge Natural History, Molluscs, 1895, pp. 193-194. These 

 observations were first recorded by Moquin-Tandon in his Mollusques de France, 

 vol. i, p. 130. 



2 John W. Taylor, Monograph of the Land and Freshwater Mollusca of the British 

 Isles (Testacellidae, Limacidae, Arionidae), Leeds, 1907, p. 37. 



