ZOOLOGY AND BOTANY, MICROSCOPY,- ETC. 637 



experiment described in the paper before us. Several flies are con- 

 fined on to a glass plate by strips of paper, and the liquid that accu- 

 mulates is sufficient to be perceptible to the naked eye ; by the help 

 of experiments with glass balls, detailed in the former paper, it was 

 ascertained that the adhesive power of the liquid was less than that 

 of water, and about equal to olive oil ; hence capillary attraction is 

 obviously the only force which could bring about the required result. 



Circulation in Ephemera Larvae.* — M. N. Creutzburg finds that 

 in the larvse of certain Ejihemerida — contrary to the statements of 

 Verloren — the vascular ampulla which supplies the caudal setae is in 

 communication with the dorsal vessel, and not with the body-cavity ; 

 this portion of the vascular system is, however, separated from the 

 dorsal vessel by a pair of valves. 



Macrotoma pluinbea.l — Dr. A. Sommer gives a detailed account 

 of this Podurid, a member of a group the anatomy of which has long 

 required revision. As in most insects the integument consists of three 

 layers — the cuticle is transparent, thin, and flexible ; the subjacent 

 matrix varies considerably in thickness in different parts of the body, 

 and its cells appear to be devoid of distinct boundaries ; the basal mem- 

 brane is structureless. 



The excretory organs are rounded in form and extend through the 

 whole of the abdomen ; the concretions are dirty white with reflected, 

 and pale green with transparent light ; they vary somewhat consider- 

 ably in form and size, but generally exhibit a distinct concentric 

 striation, like starch-granules ; they are insoluble in water and alcohol, 

 but are, when fresh, dissolved by acetic acid. The simplest muscles 

 consist of a single muscular fibre ; the muscles are not inserted 

 directly but by a tendon formed by the cuticle ; they have a finely 

 granular perimysium, in which a number of small round nuclei are 

 imbedded ; their substance exhibits transverse striation and appears to 

 be well adapted for the study of this curious phenomenon. 



The most interesting appendage of the body is the ventral tube ; 

 the numerous cells found in it are elongated oviform in shape, are 

 limited externally by a distinct membrane, and have a very finely 

 granulated protoplasm. The cuticular tubules formed by the cells 

 open to the exterior by rounded orifices, and it is clear that we have 

 here to do with unicellular glands ; their close connection with the 

 muscles of the ventral tube, leads us to suppose that when the latter 

 is put into function there is an cvagination of the connected pouches, 

 owing to the pressure of the secretion which flows out from the gland- 

 cells. If the ventral tube really serves as an organ of attachment we 

 may suppose that the secretion is a material which acts as an adhesive 

 agent. 



After describing in detail the structure of the digestive tract, the 

 auth(;r passes to the dorsal vessel and the blood ; the former is a tube 

 •which extends from the eighth abdominal segment into the thorax, 

 and passes between the dorsal longitudinal muscles ; it is continued 



* Z(X>1. Anzeig., viii. (1885; pp. 24C-S. 



t Zeitschr. f. Wise. Zool., xli. (1885) pp. 68;i-718 (2 pis.). 



