380 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and smaller the object. Insects with big eyes with several thousand facets 

 can see with tolerable distinctness. 



(6) In flight, insects can by means of their compound eyes appreciate 

 with accuracy the direction and distance (not too great) of objects. When 

 at rest they can also estimate the distance of fixed objects. 



(7) Certain insects (bees and humble-bees) can clearly distinguish 

 colour's, and that better than form. In others (wasps) the perception of 

 colour is very rudimentary. Ants perceive the ultra-violet rays (Lubbock). 



(8) The ocelli seem to furnish only very incomplete vision, and to be 

 simply accessory in the insects which possess also compound eyes. 



Function of Antennse.* — Prof. Y. Graber communicates the results of 

 further experiments on the function of antennfe. These corroborate his 

 previous conclusions, that strong smells affect the delicate portions of the 

 skin, and that finer smells useful in nutrition are in some cases certainly 

 and specially appreciated by the antennfe. The author answers some 

 apparent misunderstandings of Plateau, and proceeds to subject the experi- 

 ments of his colleague to a searching criticism, showing that Plateau's 

 'proof of the olfactory function of the antennte in the cockroach is false and 

 inadequate, though the conclusion is indeed correct. Graber chronicles 

 his own exiieriments, showing that cockroaches without feelers can hardly 

 or in no wise smell, and that the feelers really and specially act as smelling 

 organs. He does not, however, affirm this as a general proposition, since 

 some insects appear to have no sense of smell whatever, while others can 

 smell their food even when robbed of their antennae. Further details are 

 promised in a work in preparation. 



Holopneusty in Beetles.f — Dr. E. Haase communicates a note on the 

 import of the distribution of stigmata in larval beetles. Fr. Brauer (1869) 

 expressed the opinion that lank active larvae were the primary forms, and 

 the sluggish grubs secondary adaptations. Lubbock confirmed this, and 

 Palmen supported the distinction by reference to the morphology of the 

 tracheal system. In addition to three previously reported (Elmis and two 

 Lycidfe), Haase notes four cases of holopneustic larval forms (Telephorus, 

 Phengodes, Lampyris, and various DrilidaB). Insects without quiescent pupa 

 stages, with so-called incomplete metamorphosis, may be ranked along with 

 the above beetles as forms with persistent distribution of stigmata, as 

 "menotreme," — in contrast to "metatreme" insects in which the holo- 

 jmeusty of the imagines has been re-acquired in post-embryonic develop- 

 ment. According to the primary or secondary development of the mouth- 

 parts, Fr. Brauer similarly divided insects into " Meno-" and " Meta- 

 gnatha." With the exception of Elmis the holopneustic larval forms 

 mentioned belong to the Malacodermata division of beetles which in many 

 ways approach near to the primitive Coleopteran form. The individual 

 development is thus also primitive ; the larvae are comparatively like the 

 imagines, being modified only by a few secondary influences. Their 

 metamorphosis is thus in a certain way related to the anamorphosis of the 

 Hemimctabola {Homomorpha). " The quiescent pupa-stage which, though 

 ever so imperfectly, they pass through, is to be referred to and explained as 

 (in Brauer's words) ' abbreviated stages of growth,' as the secondary, almost 

 synchronous compression of several genealogically successive and distinctly 

 separate steps of developmental progress." 



labium of the Coleopterous genus StenuF.j — Hcrr F. Meinert ex- 

 plains the peculiarities in the structure of the mouth-organs of Stemis as 



* Biol. Cenlralbl., vii. (1887) pp. 13-9. t Ibid,, pp. 53-4. 



J Zool. Anzeig. (1887) pp. 136-9. 



