ZOOLOGY AND HOTANY, MICROSCOPY, ETC. 581 



walled septum from the gall bladder ; its duct joins the splenic division 

 of the pancreatic duct. 



Male Genital Organs in Sloths.*— Remy Perrier has investigated 

 the genital organs in Gholwpus didactylus and Bradypus mculliger. The 

 testes remain abdominal. There is no connection between them and the 

 inguinal region ; there is no inguinal fold or inguinal ligament. It seems 

 probable that the sloths diverged from the primitive Mammalian stock 

 before the descensus testiculorum had begun to occur. The pangolin 

 and Orycteropus which have inguinal testes, have no near relationship 

 with the American types. 



Poison in Viper's Eggs.|— C. Phisalix finds that the active principles 

 ■of the poison of Vipera aspis are present in the ova from oogenesis on- 

 wards. It is probable, he says, that other specific substances pass from 

 the blood to the ova, and have their chemical role in ontogenesis. 



Gadow's Hypothesis of Orthogenetic Variation in Chelonia4 — 

 R. E. Coker has examined nearly 250 specimens of the diamond-back 

 terrapin (Malaclemmys centrata), and finds no evidence of " orthogenetic 

 variation " in the sense that there is normally in the individual life- 

 history a progressive reduction in the number of scutes. A study of 

 a small number of specimens of Thalassochelys, on which Gadow's 

 observations were based, afforded no support for his theory. 



Minute Structure of Gecko's Foot.§— H. Schmidt has re-investi- 

 gated this interesting problem. The lappets, arising from scales, which 

 lie in a single or double row on the under side of the toes, bear on their 

 anterior third a thick cushion of very regularly arranged, extremely 

 delicate, hairs or bristles, with minute flat ends. These hairs occur in 

 tufts, which are regularly grouped in fours. Their relations with the 

 formative epidermic cells are minutely described. The hairs are really 

 •derived from modified cell-connections ; that is to say they have an 

 intercellular origin. 



Below the phalanges there is a blood chamber, or a system of blood 

 chambers, extensions of which are prolonged to the tips of the adhesive 

 lappets. The vein leading from these can be closed by an annular 

 muscular sheath. An erection-apparatus results, so that the terminal 

 surfaces of the bristles fit tightly against the surface of adhesion. 



The toe as a whole cannot adhere by atmospheric pressure, for the 

 intervals between the lappets to right and left cannot be closed. The 

 lappet of itself cannot adhere by atmospheric pressure, for it is not in 

 actual contact with the surface to which the Gecko adheres. The 

 •capacity of attachment must be in the bristles, and Weitlauer's experi- 

 ment makes it improbable that they can be fixed by atmospheric pressure. 

 Schmidt suggests that the phenomenon of adhesion is due to electrical 

 forces. 



Air-Sacs of Cham8eleons.|| — Gustav Tornier gives a full account of 

 the tracheal air-sac, which lies between the larynx and the trachea, and 



* Comptes Rendus, cxl. (1905) pp. 1054-7. t Tom. cit., pp. 1719-21. 



t Johns Hopkins Univ. Circular, No. 178 (May 1905) pp. 1-24 (7 figs.). 

 § Jenaische Zeitschr. Naturwiss., xxxix. (1905) pp. 551-80 (1 pi. and 2 figs.). 

 || Zool. Jahrb., xxi. (1904) pp. 1-40 (2 pis. and 6 figs ). 



