7DD SUMMARY OF CURRENT RESEARCHES RELATING TO 



In a subsequent note* the author remarks that in some insects 

 the thread may ho a continuous spiral ; which he speaks of as a 

 " tamidium," using the plural when the thread is not continuous. 



In the development of these structures the author finds that the 

 ectotrachea appears as a layer of nuclei which send off processes, 

 having a more internal position and running round the lumen ; it 

 is from theso prolongations that the tcenidia will he formed and hy 

 their growth and fusion give rise to tho endotrachea, of which the 

 tamidia are only hand-like thickenings, each being independent 

 and usually ring-like ; but where a trachea branches, a new series of 

 txnidia commence. 



Odoriferous Organs of Bed-bug.| — M. J. Kiinckel is of opinion 

 that the observations of Landois on the odoriferous organs of the bed- 

 bug are incomplete and inexact. Young specimens, on leaving tho 

 egg, have three odoriferous glands in the dorsal region of the abdomen ; 

 to see these glands, tho insects must not be studied when their digestive 

 tract is gorged with blood, but they must bo first made transparent. 

 These three glands remain till after tho last ccdysis, when they aro 

 replaced by thoracic and sternal glands. Tho author points out 

 that there are two systems of glands in those Hemiptcra which have 

 not been so modified as to lose their wings. Tho presence of 

 the metathoracic sternal apparatus may be taken as a criterion of 

 maturity. 



Internal Air of Insects compared with that of Leaves.! — M- J- 

 Peyron gives the results of his experiments as to the percentage of 

 oxygen contained in the air within insects. 



He kept 100 grams of cockchafers in a covered dish and drew off 

 the air each day ; in some cases at the temperature of the laboratory, 

 at others when heated in the sun, again when surrounded by ice. 

 From these experiments he concludes that as the vitality of tho 

 insects decreases, as by cold, the percentage of oxygen increases, thus 

 agreeing with the results of his experiments on leaves, and justifying 

 his idea that " the proportion of oxygen increases when protoplasmic 

 activity diminishes." 



y. Prototracheata. 



Development of Peripatus.§ — Herr J. Kennell has published the 

 second part of his essay on the development of Peripatus edivardsii and 

 P. torquaius. 



The general form of the body and its changes aro first considered. 

 The circular markings on the appendages are stated to be nothing 

 more than folds of tho epidermis, in the formation of which no share 

 is taken by cutis, connective tissue, or musculature. Segmentation 

 affects the ectoderm, and all the ventral organs remain scgmentally 



* Amcr. Natural., xx. (1886) p. 558. 



t Coinptes Kendus, ciii. (1880) pp. 81-3. 



X Ibid., cii. (1886) pp. 1339-41. 



§ Arbeit. Zool.-Zuut. lust. Wurzburg, viii. (1886) pp. l-0:_> (6 pis.). 



