222 



HARBWICKE'S SCIENCE-GOSSIP. 



The larva has apparently thirteen segments 

 (counting the head one), the three segments of the 

 thoracic region each bearing its pair of legs ; and on 

 the last segment are a pair of organs, which from 

 their structure I conceive to be suckers (Fig. 124, 

 under the I -in. obj.). The special organs, however, 

 whose functions I am unable to imagine, are found in 

 pairs upon all the segments except the first, second, 

 fourth, and last, and are quite dissimilar to any other 

 organ with which I am acquainted. 



At the first glance they bear a considerable 

 resemblance to some of the stalked diatoms 

 (Cocconema), even to the horizontal markings. 

 Various hypotheses presented themselves to my 

 mind, none of which were satisfactory; so I handed 

 over the slide to a well-known entomologist, with a 

 request that he would examine it, and tell me some- 

 thing of the function and homology of the organs in 



that the organs were internal, which point, owing to 

 the flattening of the preparation, I had overlooked. 

 A careful use of the illuminating pencil and of the 

 fine adjustment readily confirmed this point. I give 

 a drawing of one of these organs under the \-\n. obj., 

 taken from the seventh segment of one of the larvae, 

 in which the connection with the breathing-tubes is 

 more clearly shown than in any of the others 

 (Fig. 123). Under the microscope, the attachment of 

 the stalk to the integument of the larva first comes 

 into focus (Fig. 123a) ; then the diatom-like head 

 (Fig. 123$) ; while deeper still in most cases the 

 longitudinal trachea come into view (Fig. I23<r). 

 He concluded his letter by saying that the organs 

 were possibly analogous to the apparatus for pro- 

 ducing sounds possessed by some insects, which are 

 situated just inside the spiracles. Strange to say, I 

 have been unable to find any spiracles, or any 



question. It was returned with the bare statement, 

 that they were the spiracles. Now, although I make 

 no speciality of entomology, yet the constant use of 

 the microscope for over twenty years has made one 

 acquainted with the many forms of breathing-pores 

 possessed by widely different genera of insects ; and 

 these were totally distinct from any form of spiracle 

 with which I was acquainted. I wrote to my friend, 

 pointing out these differences— to the fact that there 

 was no apparent aperture, and to the more remark- 

 able fact of their being stalked, which latter point I 

 thought he had overlooked. He desired the 

 opportunity of a further examination, which, being 

 afforded him, resulted in a long letter, with 

 explanatory drawings, in reply. He acknowledged 

 having been too precipitate in designating them 

 spiracles ; but pointed out their close connection 

 with the trachea— a fact I had myself noticed ; and 



opening in the integument, except the suckers on the 

 last segment. 



Is it possible that I have mistaken the function of 

 these latter, and that they are spiracles ? I think not, 

 as they have wide, trumpet-shaped mouths, identical 

 with the suckers so common on many insects. 



In any case, here are several interesting points 

 awaiting solution, and as in some districts both the 

 beetle and its larva are readily procurable, I suggest 

 an examination of living specimens, and dissections 

 of recent ones, to those readers of Science-Gossip 

 who have the opportunity, and doubt not but that 

 some of them will be able to throw some light upon 

 what appears to me a very interesting and puzzling 

 structure in the organisation of one of our commonest 

 insects. 



J. E. Lord. 



Rawtenstall. 



