436 M. N. Cholodkowsky on the 



also agree with this. But if these organs exhibit a glandular 

 character it does not yet follow that they have a respiratory 

 function. New experiments conducted by Haase upon the 

 ventral saccules and the ventral tube prove that these organs 

 in the expanded and extended condition become filled with 

 blood ; this takes place especially in a damp and warm atmo- 

 sphere. Haase concludes from this that they represent gills. 

 It is not impossible that in certain cases the pyriform abdo- 

 minal appendages of Insect embryos may also subserve the 

 respiratory function ; such is certainly not the case in Blatta 

 germanica^ however, for here the appendages in question 

 contain no cavity whatever. However this may be, embryo- 

 logy shows us quite unmistakably that the original shape of 

 these appendages is leg-like, and that therefore their primi- 

 tive function was an ambulatory one ; it is not until later 

 that they change their form and become, owing to enormous 

 development of the ectoderm cells, glandular adhesive organs ; 

 if at the same time a cavity is preserved in them, they may 

 perhaps to a certain extent also assume the function of respi- 

 ration. It is very interesting to compare these glandular 

 appendages with the abdominal appendages of the Spiders, 

 whicli become spinnerets. In the Spiders, according to the 

 beautiful observations of Morin *, at the tip of the appendage 

 a glandular depression (the future spinneret) is formed, which 

 is altogether similar to the depressions described by Nusbaumf 

 in the abdominal appendages of Meloe \. 



I now proceed to the consideration of the other abdominal 

 appendages which persist in post-embryonic life. To this 

 category belong both the so-called pro-legs of Lepidopterous 

 and Tenthredinid larvae, and also the abdominal appendages 

 of other Insect larvse. In the paper which has been cited 

 above Herr Haase has collected a large number of facts 

 bearing on this point, so that I can dispense with their 

 enumeration. I tiierefore address myself at once to the 

 abdominal legs of caterpillars. 



As is well known, as long ago as 1869 the view was 

 expressed by Brauer § that multiped insect larvse are to be 



* Morin, '' Zur Entwicklungsgescliichte der Spiunen," Biol. Ceutralbl., 

 vi. Bd., 1887, pp. 658-663. (Also in Eussian, with plates : Odessa, 

 1887.) 



t Loc. cit. 



\ Whether the eversible caruncles described by Gerstaecker (" Ueber 

 das Vorkommen von ausstiilpbaren Anhangen am Hinterleibe von 

 Schaben," Archiv fiir Naturgeschichte, 27 Jahrg., i. Bd., 1861, pp. 107- 

 115) in Corydia also belong here is very doubtful. 



§ Brauer, " Betrachtungen iiber die Verwandlung der Insekten im Sinne 

 der Descendenz-Theorie " (with one plate), Verb, zool.-bot. Ges, Wien, 

 Bd. 19, 1869, pp. 299-318. 



