46 



SCIENCE. 



[Vol. XXI. No. 521 



which is an attempt to exhibit a portion of the internal surface of 

 a large trachea near the external orifice, the membrane being: 

 hardly more, so far as the tsenidia are concerned, than a mass of 

 wrinkles whose folds project into the lumen of the trachea and 

 are scarcely chitinous, when in that respect they are compared 

 with what, for the want of a better name, I have called the com- 

 pleted tsenidia. 



The second object of my paper is to call attention to certain 

 tracheal appendages which were discovered by Dujardin as long 

 ago as 1849, and by him referred to in a brief note published on 

 page 674 of Comptes Rendus for that year. Since then they seem 

 to have been almost forgotten. These are internal, chitinous, 

 hair-like bodies arising from the fold of the tsenidia and project- 

 ing into the lumen of the tubes. Dujardin gives a list of the in- 

 sects in whose tracheae he has seen these hairs, and remarks upon 

 the evidence which they afford as to the external origin of the 

 tracheal intima. A few scattered references to the observation 

 may be found in the European literature of the subject, with ab- 

 solutely none in this country, with the exception of one contribu- 

 tion by Dr. Henry Shimer of Mount Carroll, 111,, in an elementary 

 microscopical magazine, with one or two made by Qie in the same 

 journal, my hope being thereby to interest amateur microscopists 

 in the matter, and one or two additional notes by Mr. Fr. Dienelt 

 in a similar magazine (The Observer, Portland, Conn.), intended 

 to accomplish the same purpose. This occurred within the last two 

 years, and with these unimportant exceptions, internal tracheal 

 hairs seem never to have been noticed by any American microsco- 

 pist, although insects possessing them are not uncomtoon. My 

 own first acquaintance with them was brought about through the 

 courtesy of my correspondent, Mr. Fr. Dienelt of Loda, Illinois, 

 who sent me a slide of the tracheae from the common Colorado 

 potato beetle {Doryphora decemlineata), calling my attention to 

 certain appearances within them which he was at a loss to in- 

 terpret. These proved to be produced by tracheal hairs similar 

 to those discovered by Dujardin, and since examioing that prepa- 

 ration I have seen the appendages in the tracheae from the ovi- 

 positor of the common house fly, whilst Mr. Dienelt has observed 

 them in several other insects ; indeed, it was he who called my 

 attention to their abundance and to their great size in the tracheae 

 of Zaitha flmninea. 



Whether they are of any importance in the economy of the in- 

 sect possessing them, it is of course impossible to do more than to 

 conjecture. Dujardin has called attention to their use as evidence 

 in regard to the external origin of the tracheal membrane, re- 

 ferring to them as epidermal appendages, analogous to those of 

 the wings or of the tegument. 



In the larger tubes of Zaitha these hairs are so abundant that 

 the surface is villous with them. They gradually become fewer 

 as the tracheae ramify and grow smaller, until they entirely dis- 

 appear from the finer divisions. They arise from the chitinous 

 folds of the membrane, rarely from the intima itself between the 

 tsenidia, and extend obliquely into the lumen, their free extremi- 

 ties usually being directed toward the spiracle. They are hollow, 

 their minute lumen communicating distinctly with that of the 

 taenidium, to which they are attached, or from which they arise 

 by an enlarged base. Their length averages about ^J-j of an inch, 

 although it is difiScult to measure them with any accuracy, as 

 they are rarely straight. The free extremity of each tapers to an 

 exceedingly fine point, which is sometimes bifid, occasionally 

 trifid. In Fig. 4 several are shown attached to the wrinkles of 

 the tracheae near a spiracle, and in Fig. 5 is exhibited a transverse 

 section of a tube with the hairs projecting into its lumen. 



The third and last of the points to which this paper is devoted 

 is one which, so far as I have been able to ascertain, has not been 

 previously observed as a part of the structure of any insect's 

 tracheae. These are certain minute, elliptical bodies in the 

 tsenidia, each with an internal, presumably glandular, appendage, 

 to all appearance forming part of the taenidium from which it 

 springs. Whilst these are numerous in the main trunks and in 

 the larger branches where the hairs are abundant, ihey are more 

 conspicuous and seem also to be more numerous in those that bear 

 but few of these internal filamentous appendages. 



The external bodies were at first supposed to be the remains of 



hairs which had been broken away in the preparation of the 

 tracheae for microscopical study, but further examination soon 

 dispelled that illusion, as the objects difl'er widely from the bases 

 of the hairs, which are only thick-walled circular openings. The 

 enigmatical bodies are more or less elliptical or elongate-ovate in 

 contour, no two being of precisely the same shape nor of the same 

 size, although in size they are rather more constant, the diameter 

 varying from j^\,5 to y^'j^ of an inch, the length externally being 

 about ^05 of an inch, or but little longer than the diameter of a 

 human red blood-corpuscle. They are commonly in the taenidia, 

 the lateral margins of the fissure within the latter separating to 

 give them space, and they are perforated in the most irregular 

 way, the small apertures varying in number and in form as the 

 bodies themselves vary in shape, the openings occasionally being 

 reduced to a single circular one. These objects are shown in 

 Fig. 1, within the short taenidium beside the second on the left- 

 hand side; in Fig. 3, where there are two in the broad, shallow 

 folds of the membrane, and more in detail by Fig. 6. 



Here again enters another application of the diatomist's black 

 dot resolution which has made plain the structure of the secondary 

 membrane of so many of those plants. In Fig. 6 the black dot 

 resolution shows the perforations, which are always irregular in 

 number and in form, with the space between the uneven edges 

 of the taenidium, and, in the sketch on the right-hand side, the 

 continuation of an aperture with the taenidial fissure. 



These elliptical, cribriform bodies seldom occur on the tracheal 

 membrane between the tubules. Occasionally they are seen to 

 form the principal portion of a short, otherwise solid, taenidium, 

 which to all appearance has been produced only to accommodate 

 that special object. In such cases there is but one; usually a 

 single tubule possesses several. 



The perforations pass through the substance of the taenidium 

 and are received, usually by means of a short pedicle, inacushion- 

 like, apparently glandular, body attached to the inner surface and 

 projecting into the lumen of the trachea. In Fig. 7 are shown 

 three of these glandular bodies, if they are glandular; and it is 

 equally difficult to suppose that they are and that they are not. 

 They appear under the microscope as collections of exceedingly 

 minute, rounded apertures, which, in certain positions, may be 

 seen to be continuous with narrow passages directed toward the 

 pedicle, when that exists, and toward the external cribriform 

 plate. Their structure in minuteness is comparable with the sec- 

 ondary structure of the diatoms, which I have so often mentioned, 

 being as exquisite and as difficult to resolve, in this taxing the 

 good qualities of the microscopist's best objectives. The thickness 

 of the cushion-like objects is about ^^^ of an inch, a space capable 

 of being occupied by much microscopic structure. 



Although they do not commonly occur on the tracheal mem- 

 brane between the taenidia. they may be found there, as shown in 

 Fig. 4, where is delineated a portion of a crumpled region of the 

 membrane near a spiracle, with a few hairs and with several of 

 these problematical, presumably glandular, bodies scattered about 

 ike so many islands in a sea of wrinklf s. 



• What their function may be it is difficult to conjecture. Their 

 position within the lumen of the tracheae, and their connection 

 with the external cribriform spaces, in no way simplify the problem. 



Their presence, however, seems to add a unique scientific value 

 to the tracheal tubes of Zaitha fliiminea, to say nothing of mi- 

 croscopical interest. A microscopist, with a well-trained and 

 intelligent microtomist to do his bidding, might be able to add 

 much to our knowledge of the structure, not only of these appar- 

 ently glandular organs of the pedicle and the perforated, elHptical 

 objects, but of certain other regions of these remarkable tracheae. 



CURRENT NOTES ON ANTHROPOLOGY.— XXI. 



[Edited by D. G. Brinton, M.D., LL.D.] 



The So-Called Caucasian Race. 



In a paper which he presented to the Moscow Congress last 



summer, M. Ernest Chantre, well known for his profound studies 



in the ethnology of north-western Asia, enters a remonstrance 



against the erroneous use of the term " Caucasian Race," as 



