2 54 ENTOMOLOGISK TIDSKRIFT 1917. 



an auditory function he took a leg of a living animal, laid 

 it instantly under a microscope arranged for enlarging about 

 600 times, and when he then produced a somewhat deep 

 tone on a violin, he saw that the distal part of such a hair 

 vibrated; a few minutes after the leg had been torn oft" the 

 blood was coagulated, and then the sound of the violin could 

 not produce any vibration. 



In 1888 W. Wagner published an interesting paper: 

 Des Poils nommés auditifs chea les Araignées. He critisized 

 Dahl's first paper, but seems to have overlooked the second. 

 He gave a very detailed account of the differences found by 

 him in the modes of insertion, etc., between the types of 

 sensory hairs compared with each other and with normal 

 protecting hairs. The zoologist interested in the matter must 

 read his paper, but some main points may be briefly men- 

 tioned here. He discerned between »simple tactile hairs» 

 and the »hairs called auditory». The hairs of the first-named 

 kind do not project from a calicle, but their base, »radix», 

 is much thickened, so that the surrounding, somewhat eleva- 

 ted part of the skin becomes removed from the subbasal 

 part of the hair. The hair named auditory projects through 

 the constricted opening of a large calicle, on the bottom of 

 which is found (in Araneae) a flat calicle or cup, and in the 

 middle of this cup the hair is inserted. Furthermore Wagner 

 described two forms of such hairs differing from one 

 another in thickness, length and other minor particulars, and 

 he named them respectively «poils à chapelets» and «poils 

 tactils fins». On the tarsus of a species of Mygale he found 

 a third type, viz. a very short hair consisting af a short stalk 

 and an oblong-oval plate, while the stalk protrudes from a 

 calicle which is lower with a comparatively wider opening 

 than in the «poils à chapelets». Unfortunately Wagner said 

 next to nothing on the occurrence of the types in genera or 

 families. He has made an experiment as to the vibration of 

 the so-called auditory hairs, but with a negative result, and 

 he could not accept Dahl's interpretation of their function, 

 but he considered all types of sensory hairs on the legs of 

 Aranese as tactile organs, suggesting the possibility that the 



