ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 51 



in contact witli air and forms the seta. The sucking apparatus of 

 Aphides has much resemblance to, but is simpler than that of the 

 Coccid^e. After a description of the digestive apparatus and the 

 Malpighian vessels, the author states that the dorsal vessel cannot be 

 made out either in adult or in larval forms ; in the embryo, however, 

 as Mecznikow has shown, it may be recognized as a long tube, the 

 wall of which consists of a single layer of small flattened cells, fused 

 with one another ; very thin muscular fibres pass, rather irregularly, 

 along and obliquely across it. 



With regard to the generative organs, the present investigations 

 have led to results far from accordant with those of Balbiani ; thus 

 the " antipodal " cell could not be detected, but in an advanced stage 

 of development a rounded protoplasmic-body at the hinder pole of the 

 egg was observed to have the same characters as the peripheral pro- 

 toplasmic layer. Germinal vesicles were on many occasions distinctly 

 seen. The formation of the blastoderm proceeds from behind forwards, 

 and cleavage is essentially equal. 



Lampyridse.* — H. Eitter v. Wielowiejski finds that : — 



1. The tracheal end-cells discovered by M. Schultze are not, as 

 their name implies, true endings of the respiratory tubules, for they 

 ramify into still finer capillary tubes, in which the chitinous spiral 

 support is absent ; these latter are very long, and, invested by 

 their peritoneal membrane, are largely distributed in the luminous 

 tissue. 



2. It is only comparatively rarely that the " tracheal capillaries " 

 end blindly in the luminous organs ; they more generally anastomose 

 with one another, and form a kind of irregular plexus. 



3. These structures do not, however, make their way into the 

 interior of the parenchymatous cells, but extend richly over their 

 surface, where they form irregular loops. 



4. The " tracheal end-cells " are nothing more than the enlarge- 

 ment of the membranous peritoneal layer at the base of the tracheal 

 capillaries, which radiate out from a trachea with a chitinous spiral ; 

 and the whole arrangement may be homologized with certain embryonal 

 conditions of the tracheal system. 



5. The " end-cells" do not form the seat or the starting-point for 

 the development of the light. Although this phenomenon may first 

 appear in their vicinity this is only because a large store of oxygen 

 has been laid up in them. 



6. The luminous property is essentially connected with the 

 parenchymatous cells of the luminous organs, and is due to the slow 

 oxidation of a substance formed by them, under the control of the 

 nervous system. 



7. The parenchymatous cells, from which the two layers found on 

 the ventral luminous organs are formed, are exactly comparable in their 

 morphological characters ; and the difference between them is solely 

 due to the chemical characters of their contents. 



* Zeitschr. f, Wiss. Zool,, xxxvii. (1882) pp. 354-i28 (2 pis.). 



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