ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 553 



tions made with osmic acid showed that the smooth terminal branches 

 of the tracheae always end freely, and that they are never connected 

 with other capillaries, either of their own or of other trunks; the 

 author is so certain of this that he thinks that the anastomoses 

 observed by Kolliker and others in the Lampyridse can have no real 

 existence. The structure of the dorsal layer of the luminous plates 

 is very simple, no distinct cellular elements could be isolated, and 

 the organs whether fresh, or after treatment with various reagents, 

 showed nothing but opaque uric concretions floating in large numbers 

 in the fluid. 



On comparing the luminous plates of Luciola with the light- 

 giving organs of other Lampyridae we are able to compare the clear 

 cellular elements of the cylindrical lobules, which surround the vertical 

 tracheal limbs and their branches, with the terminal tracheal cells 

 described by M. Schultze. 



In Luciola the arrangement and distribution of the elements is 

 much more regular than in other forms, and the plates appear to have 

 attained to a much higher and more complete grade of development, 

 as is expressed by the regular structure of the lobes, and by the 

 special development of the tracheal end-cells, as well as by the constant 

 dichotomous division of the termination of the tracheae. 



The author discusses the homodynamy of the luminous organs with 

 portions of the fat-body, and finds powerful evidence in support of it in 

 the complete agreement in form, size, and relation to reagents exhibited 

 by the nuclei of the luminous organs on the one hand, and of the 

 fat-body on the other. With regard to the loss of substance by 

 Luciolce, Emery's observations lead to the conclusion that a luminous 

 and flying specimen loses daily about half a milligram in weight ; it 

 is to be borne in mind that the imagines eat nothing. 



In conclusion, the physiology of the luminous activity is discussed. 

 The males are either luminous for short and regular periods, or, when 

 seized or injured, are without intermission, though not so remarkably, 

 brilliant. In the latter case, which, it is clear, is the only one on 

 which observations can be made, bright rings are seen on a dark back- 

 ground, and it would appear that the luminous oxidation takes place 

 at the surface of, but outside the substance of the parenchymatous 

 cells. These appear to secrete the luminous material, which is taken 

 up by the tracheal end-cells, and burnt by means of the oxygen in the 

 fine branches of the tracheae. This combustion can only take place 

 when the chitinous membrane of the tracheae is extraordinarily fine. 



The author does not think that this luminous power is a sexual 

 means of exciting the rare females, but rather that it is a kind of warn- 

 ing to insectivorous nocturnal animals ; the unpleasant smell which a 

 Luciola gives off" on injury makes it perhaps disagreeable to bats or 

 other nocturnal animals. 



Development of (Ecanthus niveus and its parasitic Teleas.* — 

 H. Ayers finds that the ovum of (Ecanthus — the tree-cricket — arises 



• Amer. Nat , xviii. (1884) pp. 537-40 ; from Proc. Boston Soc. Nat. Hist., 

 1884, 56 pp. (8 pis.). 



Ser. 2.— Vol. IV. 2 P 



