i8y5. SOME RECENT INSECT LITERATURE. i8r 



upon examination, to belong to a form of the common species 

 Chironomus plnmosus. But Herr Schmidt does not consider that the 

 shining serves any useful purpose, such as that of attracting a mate. 

 It rather appears to be due to the presence of injurious micro- 

 organisms in the body, as all the luminous midges observed were 

 exceedingly sluggish and apparently sickly. The presence of bacteria 

 was, however, not definitely proved by microscopic research. Herr 

 Schmidt compares these insects with a luminous crustacean (Talityns) 

 described a few years ago by M. Giard. This shining individual was 

 evidently sick, being far more sluggish than his companions, 

 and only surviving a few days. Microscopic examination here 

 revealed swarms of Micrococci in the foot, while healthy, non- 

 luminous Talitri inoculated with these became in their turn shining 

 and sickly. 



A lengthy, minute, and laborious memoir on the glands of the 

 Hymenoptera has lately been published by another French naturalist, 

 Mr. L. Bordas (6). He has investigated the salivary glands, the food 

 canal, the renal (Malpighian) tubes, and the poison-glands in several 

 genera of most of the larger groups of the Hymenoptera, comparing 

 the varying developments of corresponding organs in each. Six sets 

 of salivary glands were found in almost all the insects of the order 

 examined, while four other sets were found in some instances. Some 

 of these are grape-like (racemose), consisting of numerous follicles, 

 while others are unilocular ; the ducts of the racemose glands are 

 spirally strengthened, like tracheal breathing-tubes. Mr. Bordas 

 correlates each pair of glands with a primitive segment of the head, 

 but careful embryological research will be needed to confirm such a 

 speculation. The food canal is described as it occurs in insects of the 

 various families, and its different regions — fore-gut (comprising 

 pharynx, gullet, crop, and gizzard), mid-gut, and hind-gut, including 

 the rectum — are compared, their elaboration being traced through 

 the pupal stage, from the comparatively simple digestive tract of the 

 larva. The Malpighian tubes in larvae are only four in number ; 

 during the pupal state these disappear, and a much larger number 

 of tubes is developed for the perfect state. These are more 

 numerous in the Hymenoptera than among insects of any other 

 order, more than a hundred being sometimes present ; their number 

 is, generally speaking, inversely proportional to their length. 

 Mr. Bordas accepts the view, now generally held, that the 

 function of these tubes is renal; it will be in the remembrance of 

 students of insect anatomy that Mr. Lowne, in his recent work on 

 the blow-fly, maintains the older view that their function is rather 

 hepatic. 



The most interesting section of Mr. Bordas' work is, perhaps,, 

 his description of the poison-glands in various Hymenoptera. He 

 states that hitherto only those of the hive-bee have been described, 

 and he now figures the organs in many other insects of the order. 



