410 PROCEEDINGS OF THE ACADEMY OF [May, 



In all the experiments of various kinds 173 individuals have been 

 used. In conclusion the evidence favors the view that the lyriform 

 organs function only as olfactory organs. 



5. Discussion. 



(a) Function of the Lyriform Organs. 



Bertkau (1878) supposed that they have an auditory sense. Dahl 

 (1883) thought that organ No. 13 on the metatarsus was an apparatus 

 to help in the spinning ; since the same organ is found in other members 

 of the arachnid group which do not spin, this hypothesis is no longer 

 admissible. Vogt and Yung (1894) suggest that these organs have a 

 respiratory function. They made this statement based upon a sup- 

 posed vessel placed below the organ as described by Dahl. Since this 

 vessel never existed their suggestion can have no force. Schimke- 

 witsch (1885) attributes an auditory role to them, and thinks that they 

 play the same part as do the "chordotonales" of Graber which are 

 found in adult insects and their larvse. This function is not yet 

 sufficiently demonstrated in insects. Wagner has the same opinion 

 as Bertkau and Schimkewitsch, but since none of these preceding 

 observers have performed any experiments to prove their views we 

 need not further consider their hypotheses. 



Gaubert concludes that the lyriform organs are an apparatus for 

 perceiving heat and probably the sense of humidity and senses in 

 general. He varnished (but does not say with what kind of varnish) 

 the lyriform organs of several Lycosas carefully so that no more of 

 the surface was covered than necessary and so that the varnish did 

 not interfere with the articulations. These specimens and several 

 which had not been varnished were placed in a large glass vessel. 

 In one end of this vessel he placed a shelter or protection and, when 

 the spiders had come to rest, the other end of the vessel was lowered 

 into hot water. He says: "Quand la temperature commence a 

 s'elever les Araignees n'ayant subi aucune preparation abandonment 

 leur retraite et se dirigent vers 1' autre partie du bocal, celles qui ont 

 les organes lyriformes vernis ne cherchent a fuir qu' on moment apres, 

 lorsque la temperature est plus elevee." 



(b) Olfactory Experiments. 



Robineau-Desvoidy (1842), according to Packard (1887), said that 

 the olfactory sense of spiders is very well developed and localized in 

 the mandibles. 



