724 SUMMARY OF CURRENT RESEARCHES RELATING TO 



kind in the form of bent or straight sctsc, which arc very strongly 

 cliitinizeil, and apjiear to be connected with a wineglass-shaped poie- 

 cannl, by nieiuis of a chitinous ni(^mbiane ; the pore-canal in its narrower 

 lower part was, as a riilo, filled by a homogonuons mass, which was 

 found to bo coloured red by cariniiic. The olfactory organs may bo in 

 the form of cones placed on the surface or in pits ; the typical structure 

 of the former has already been investigated by Lcydig in the Ilymeno- 

 ptera. Organs of this kind appear to bo found not only in all orders of 

 Insects, but also in TNIyriopoda and Crustacea ; they may, therefore, be 

 regarded as the chief form of olfactory organ among Arthropods. When 

 the couo is placed in a pit there may bo one (simple pits) or several 

 cones (comi)ound pits) ; these cones agree in all essential points witli 

 tlioso which are set on the surface. The differences in the pits are fully 

 pointed out. 



The auditory organs are not hair-like structures; they were first 

 distinguished by Krajjelin, who culled them pore-plates ; there is a firm, 

 thick membrane, without any orifice, which completely shuts oft" the 

 lumen of the pore-canal from the outer air. The author's observations 

 on the structure of these organs confirms Kriipelin's account. When 

 separate antenna) of Hymenoptcra were boiled with concentrated potash 

 the plates were found, after the disajipearance of all the soft parts, to bo 

 completely uninjured and to still lie in their original position ; this 

 showed that they did not consist of modified nerve-substance, but of firm 

 chitin. In VesjJa crahro the greater part of the pore-canal closed by the 

 plate was seen to be filled by epithelial cells ; through these there 

 extends a central nerve-cord which arises from the basal ganglion. Just 

 below the pore-plate there is a cavity closed by two plates, which at 

 first lie close to one another, but then separate ; these are connected with 

 a hyaline intermediate piece of the ring. It seems to bo clear that tlio 

 nerve from the ganglion is not directly inserted into the pore-plate, but 

 its exact course could not be made out. As the structure of this organ 

 forbids us from regarding it as either tactile or olfiictory, HtaT Rulaud 

 thinks it probable it is auditory ; the form and mode of attachment of 

 the i>lates are such as to adapt it to vibratory movements, and the cavity 

 below is such as we might expect to find in an auditory organ. 



The structures were also examined in Ichneumonidaj, Cynipidfe, and 

 the Ants ; in the last of which they were the most complicated. Pore- 

 plates were also found in the coleopterous genus NecropJiorus. 



Poison of Hymenoptera.* — M. G. Carlct has a note on the poison of 

 Hymeuoi)tera with a smooth sting, and on the existence of a poison- 

 chamber in the Mellifera. The forms examined were Philanthus, 

 Pomjjilus, and others. In them the alkaline gland, which the author 

 has already ?hown to be well-developed in the Bee and others, is rudi- 

 mentary. These are the Hymenoptera whose incomplete poison does 

 not kill the insects with which they provision their nest, for the purpose 

 of feeding their larvae with living prey. In M. Carlet's opinion it is the 

 presence of two liquids or of one only which produces respectively the 

 mortal poison or the anaesthetic, and not the asserted power to select the 

 point of the body at which the Hymenopteron will sting its victim. 



The poison-chamber is useful as furnishing poison immediately to 

 the Hymenopteron, while it protects the poison from the air which would 



• Comptea Kcndus, cvi. (1888) pp. 1737-40. 



