INDUSTRIAL PROGRESS DURING THE YEAR 1871. c li 



tracheal gills, have hitherto been known to exist in the adult, 

 winged state of but one genus of insects (Pteronarcys). Dr. 

 Gerstaecker now finds that an European Nemoura and a 

 Siberian and Chilian genus of stone-flies also possess them. 



For about a month during the last part of April and early 

 in May last Dr. Packard was engaged in exploring the caves 

 of Kentucky under the auspices of the Geological Survey of 

 that state, Professor Slialer director. He first examined the 

 Mammoth Cave, and doubled the number of animals known 

 to exist therein, and in others adjoining. An exploration 

 with Professor Slialer of the Carter Caves in Gravson Conn- 



mi 



ty, Kentucky, also revealed a rich fauna composed of twen- 

 ty species. Dr. Packard also examined Wyandotte Cave 

 alone, and found a wingless Psocus and two species of Thy- 

 sanura, new to the cave. Several caves within sixteen miles 

 of New Albany, Indiana, at Bradford, were examined in 

 company witli Dr. Sloan. Finally, a careful examination of 

 Weyer's Cave, in Virginia, and the adjoining Cave of the 

 Fountains, revealed a fauna containing some twenty species, 

 no life having been previously reported from those caves. 

 The most important discoveries were the larvae of the blind 

 beetles, Adelops and Anopthalmus, and a new species of 

 Jtirpyx, a genus not before detected in the United States. 



The results show a great uniformity in the distribution 

 of life, more than would at first be expected, though these 

 caves lie in a faunal region nearly identical as regards the 

 external world ; and the temperature of the caves is very 

 constant. Still some notable differences occurred. 



The phosphorescent organs of Elcder noctilucus have been 

 investigated recently by MM. Robin and Laboulbene, who 

 state (Comjrtes Renclus, Vol. LXXVII.,No. 8) that the light 

 first appears in the centre, then spreads throughout. A yel- 

 low linear zone of adipose tissue at the exterior, at length 

 becoming luminous, is yet not photogenic ; it only reflects 

 the light produced by the central part. But it does so not 

 only from its internal face, but throughout its thickness, the 

 action being favored by the transparency and high refringent 

 power of the fatty globules. The phenomena of dispersion 

 and interference thus produced are the cause of the remark- 

 able brilliancy appearing when the light from the centre 

 reaches as far as this zone. As to the changes of molecular 



