Slugs as Mycophagists. A. H. R. Buller. 281 
decomposed. I set the two heaps of fruit-bodies on the gravel 
4 ft. apart and each 21 ft. distant from the place in the border 
from which the slugs usually issued on their nocturnal forays; 
but the new position of the fungi was such that the slugs, if 
they sought the fungi, would be obliged to travel not in the 
direction taken during the previous two nights but in a direction 
making therewith an angle of 45°. The night was very still, 
and dark; there was no moon, and overhanging trees shut out 
from that part of the gravel which the slugs would be obliged 
to cross even the faint light of the stars. At 11.30 p.m., with the 
help of a taper, I found a slug moving toward the two heaps of 
fungi and only 9 ft. distant from them. It was a Limax maximus, 
exactly resembling the two I had seen the previous night, and 
its four horns were spread out in the air as though they were 
being used to detect the direction from which the odour of the 
fungi was coming. I could see by the slime-trail upon fallen 
leaves and gravel stones that the slug was making a gentle 
sweep toward the Russula nigricans fruit-bodies and that it 
had kept upon a steady course since it had left the border. 
Next morning, I found that the Russula nigricans fruit-bodies 
had been visited by two slugs during the night, for there were 
four slime-tracks passing between them and the border. More- 
over, one large cavity and two smaller ones had been made by 
the slugs in one of the pilei. By careful tracking, I found that 
one of the slugs which we will assume was homeward bound, 
after feeding upon one of the Russula nigricans fruit-bodies, 
had made a détour and had visited the heap of Cortinarius 
caninus fruit-bodies. Here it had crept on to one of the pilei 
and tasted the gills, and then it had retired by a somewhat 
sinuous course to the border from which it had set out, 21 ft. 
away. The actual distance traversed by this slug in the course 
of its excursion to the two heaps of fungi must have been at 
least 50 ft. 
The circumference of a circle with a radius of 21 ft. is 132 ft. 
The width of my heap of Russula nigricans fruit-bodies was 
4 inches. Supposing, therefore, that the heap of fruit-bodies 
were on the circumference of a circle with a radius of 21 ft., 
as was actually the case in the experiment just recorded, and 
supposing, further, that a slug were to start from the centre of 
this circle and move at random radially outwards for a distance 
of 21 ft., the chances of the slug meeting the heap of fruit-bodies 
would be 395 to I against. Simple mathematical calculations 
of this kind afford strong evidence that the slugs in my experi- 
ments did not find the fungi in the night by chance but through 
the guidance of some stimulus coming from the fungi and re- 
ceived by their sense organs. 
