484 



NATURE 



{April 1 8, 1872 



different to that previously noticed. The whole flame was 

 tinged with the colour imparted to it. A mere trace of 

 hydrochloric acid gas imparts a reddish brown to the 

 flame ; ammonia gas gives a yellow, and burns freely. 

 It is striking to note the combustion of ammonia gas 

 rising from an unstopped bottle that contains the usual 

 solution and which is placed below the flame. 



But carbonic acid gas yields the most striking result in 

 contact with the flame. A pale lilac tinge is instantly 

 produced by a stream of this gas. This, I imagine, is 

 due to the decomposition of the carbonic acid by the 

 hydrogen, and the production and combustion of carbonic 

 oxide. For it is at the lower part of the flame that the 

 effect is most marked. One per cent, of pure carbonic 

 acid admitted to a jar of air, can be detected on holding 

 the jar over the flame. The breath, of course, shows the 

 effect most strikmgly. 



IX. Here then is an eminently practical method of noting 

 the presence of vitiated air in rooms or public buildings. 

 A continuous hydrogen apparatus might be employed 

 with a wash bulb attached. The flame might be burnt 

 from a brass burner or lava jet, placed within a blackened 

 tin cylinder. Opposite the flame a hole might be pierced 

 in the cylinder, and closed by a lens for better viewing 

 the flame within. As soon as the atmosphere in a room 

 becomes unpleasantly vitiated the flame would indicate 

 the fact by its changed colour. A similar apparatus 

 might likewise be employed by miners : in metal mines as 

 a warning against impure air, and in coal mines as a de- 

 tector of Are damp. In this latter case the ends of the 

 cylinder could be covered with wire gauze. 



To this practical aspect of the question 1 am now giving 

 such little leisure as I possess. 



The results thus briefly described demonstrate — 



1. That the combustion of hydrogen exhibits some 

 physical peculiarities, and produces phosphorescence on 

 many substances with which it comes in contact. 



2. That the blueness so often seen in a hydrogen flame 

 is due to the presence of sulphur, derived either from the 

 vulcanised lubbcr tubing, or from atmospheric dust, or 

 from the decomposition of the sulphuric acid spray from 

 the generator. 



3. That a flame of hydrogen forms an exceeedingly 

 delicate re-agent for the detection of sulphur or phos- 

 phorus, and possibly also of tin. 



4. That many sulphates, and also carbonic acid, are 

 apparently decomposed by a hydrogen flame. 



5. That a hydrogen flame is further a test for the pre- 

 sence of some gases, notably carbonic acid. 



6. That these results are capable of practical applica- 

 tion. W. F. Barrett 



International College, Spring Grove, W. 



THE INHABITANTS OF THE MAMMOTH 

 CAVE OF KENTUCKY 



Cru.staceans and Insects 



[Concluded from page 448) 



■NT EXT to the blind fish, the blind crawfish attracts the 

 -"■^ attention of visitors to the cave. This is the Cambarus 

 pcllucidiis (Fig. 10, p. 4S6, from Hagen's monograph of the 

 North American Astacida') first described by Dr. Tell- 

 kampf. He remarks that " the eyes are rudimentary in the 

 adults, but are larger in the young." We might add that 

 this is an evidence that the embryo develops like those of 

 the other species ; and that the inheritance of the blind 

 condition is probably due to causes first acting on the 

 adults and transmitted to their young, until the produc- 

 tion of offspring that become blind becomes a habit. This 

 is a partial proof at least that the characters separating 

 the genera and species of animals are those inherited from 

 adults, modified by their physical surroundings and adap- 



tations to changing conditions of life, inducing certain 

 alterations in parts which have been transmitted with 

 more or less rapidity, and become finally fixed and 

 habitual. Prof. Hagen has seen a female of Cambarus 

 j5'rt;/o/i'/z from Mammoth Cave, "with the eyes well de- 

 veloped," and a specimen was also found by Mr. Cooke. 

 Prof. Hagen remarks that " C. pclhuidus is the most 

 aberrant species of the genus. The eyes are atrophied, 

 smaller at the base, conical, instead of cylindrical and 

 elongated, as in the other species. The cornea exists, but 

 is small, circular, and not faceted ; the optic fibres and 

 the dark-coloured pigments surrounding them in all other 

 species arenot develoLcd." It seems difficult for one to 

 imagine that our blind crawfish was created suddenly, 

 without the intervention of secondary laws, for there are 

 the eyes more perfect in the young than the adult, thus 

 pointing back to ancestors unhke the species now ex- 

 isting. We can now understand, why embryologists 

 are anxiously studying the embryoL'gy of animals to 

 see what organs or characteristics are inherited, and what 

 originate de novo, thus building up genealogies, and form- 

 ing almost a new department ot science, — comparative 

 embryology in its truest and widest sense. 



Of all the animals found in caves, either in this country 

 or Europe, perhaps the most strange and unexpected is 

 the little creature of which we now speak. It is an Isopod 

 crustacean, of which the pill bugs or sow bugs are ex- 

 amples. A true species of pill bug {Titanethes albus 

 Schiodte) inhabits the caves of Carniolia, and it is easy to 

 believe that one of the numerous species of this group may 

 have become isolated in these caves and modified into its 

 present form. So also with the blind Niphargus stygius 

 of Europe, allied to the fresh water Gammarus so abun- 

 dant in pools of fresh water. We can also imagine how 

 a species of Asellus, a fresh water Isopod, could represent 

 the ldoteid;r? in our caves, and one may yet be found; 

 but how the present form became a cave dweller is diffi- 

 cult of explanation, as its nearest allies are certain species 

 of Idotea which are all marine, with the exception of two 

 species : /. entonion, living in the sea and also in the 

 depths of the Swedish lakes, as discovered by Loven, the 

 distinguished Swedish naturalist, while a species repre- 

 senting this has been detected by Dr. Stimpson at the 

 bottom of Lake Michigan. Our cave dweller is nearly 

 allied to Idotea, but differs in being blind, and in other 

 particulars, and may be called Ccccidotea stygia* (Fig. 

 II side view, enlarged; Fig. 12 dorsal view ; b, inner 

 antenna ; c, ist leg.) It was found creeping over the fine 

 sandy bottom, in company with the Campodea, in a shal- 

 low pool of water four or five miles from the mouth of the 

 cave. 



This closes our list of known articulates from this and 

 other caves in this country, the result of slight explora- 

 tions by a few individuals. The number will doubtless be 

 increased by future research. It is to be hoped that our 

 western naturalists will thoroughly explore all the sinks 

 and holes in the cave country of the western and middle 

 states. The subject is one of the highest interest in a 

 zoological point of view, and from the light it throws on 



' Generic characters. Head large, mucli thicker than tlie body, and 

 as long as broad : subcylindrical, rounded in front. No eyes. First an- 

 tenna:: slender, S-jointed (2nd antenna; brolcen oft"). Abdominal segments 

 consolidated into one piece. Differs chiefly from Idotea, to which it is 

 otherwise closely allied, by the 8-jointed (irstead of 4-jointed 1st (inner) 

 antenna;, the very large head, and by the absence of_ any traces of the 

 three basal segments of the abdomen usually present In Idotea.^ Specific 

 characters. fcody smooth, pure white : tegument thin, the viscera ap- 

 pearing through. Head as wide as succeeding segment, and a little more 

 than twice as long. Inner antennse minute, slender, the four basal joints 

 of nearly equal length, though the fourth is a little smaller than the basal 

 three, remaining four joints much smaller than others, being one-half as 

 thick and two-thirds as long as either of the four basal jomts ; ends cf 

 last four joints a little swollen, giving rise to two or three hairs ; termini! 

 joint ending in a more distinct knob, and bearing five hairs. Segment of 

 thora.\ very distinct, sutures deeply inci-ed : edges of segments pilose : 

 abdomen flat above, rounded bthind, with a very slight median projec- 

 tion : the entire pair of gills do not reach to the end of the abdomtii, 

 and the inner edges diverge posteriorly. Legs long and slender, ist pair 

 shorter, but no smaller than the second. Length '25 inch. 



