EXPERIMENTS ON THE ORGANS OF SMELL 2G9 



Experiments made by placing the antennae in liquid paraffine so 

 as to cover them with a layer of paraffine, thus excluding the air, 

 gave the same result as if the antennae had been removed. 



The experiments may be divided, according to their object, into 

 three groups. Experiments of the first kind were made on insects 

 in their relation to strong-smelling substances, as turpentine, carbolic 

 acid, etc., before and after extirpation of the antennas. The second 

 groirp embraces experiments on the relation of animals as regards 

 their search for food ; and finally the third group embraces experi- 

 ments on the relation of the sexes relative to reproduction before 

 and after the extirpation of the antennae. 



Relation of insects to smelling substances before and after the loss of 

 their antennae. Taking a glass rod dipped in carbolic acid and hold- 

 ing it within 10 cm. of Philonthus ceneus, found under stones at the 

 end of February, it was seen to raise its head, turn it in different 

 directions, and to make lively movements with its antennae. But 

 scarcely had Hauser placed the rod close to it when it started back 

 as if frightened, made a sudden turn, and rushed, extremely dis- 

 turbed, in the opposite direction. When he removed the glass rod, 

 the creature busied itself for some time with its antennae, while it 

 drew them, with the aid of its fore limbs, through its mouth, 

 although they had not come into direct contact with the carbolic 

 acid. There was the same reaction against oil of turpentine, and it 

 was still more violent against acetic acid. 



After having many times carefully tested the relations of the 

 normal animal to the substances mentioned, the antennae were re- 

 moved from the socket-cavity. 



On the second day after Hauser experimented with the insects, 

 they exhibited no reaction either against the carbolic acid, the oil of 

 turpentine, or even against the acetic acid, although he held the glass 

 rod which had been dipped into it for one or two minutes before and 

 over the head. The creatures remained completely quiet and im- 

 movable, at the most slightly moving the palpi. They showed 

 otherwise no change in their mode of life and their demeanor ; they 

 ate with great eagerness flesh which had been placed before them, 

 or dead insects, and some were as active as usual as late as May. 

 These beetles had, as proved by the experiments, lost the sense of 

 smell alone ; how far the sense of touch was lost Hauser could not 

 experimentally decide. 



The same results followed experiments with species of the genus 

 Ptinus, Tenebrio, Ichneumon, Formica, Yespa, Tenthredo, Saturnia, 

 Vanessa, and Smerinthus ; also many species of Diptera and Orthop- 



