ZOOLOGY AND BOTANY, MICROSCOPY, ETC. L53 



Placentation in Tatu.* — H. H. Lane has studied the habits and 

 placentation of Tatu novemcinctum var. texamim, the only Edentate 

 living in the United States at the present time. It gives birth usually 

 to four young in a litter. The uterus is simple and globular, the ovi- 

 ducts are only slightly convoluted. Each foetus develops within its 

 own amniotic sac, though a common chorionic vesicle serves for all. 

 While the evidence is not decisive, the fact that the young were all of 

 the same sex in the case studied, as well as the fact that all lie within a 

 ■common chorionic vesicle, may be held to favour the view that there is 

 poly em bryony (von Jhering, Newman and Patterson), and that the sex is 

 determined in the fertilised ovum. The chorionic villi vary from short 

 simple ones to long arborescent ones. The short villi form two longi- 

 tudinal bands, separating two discoidal areas of the long villi. The 

 placenta is of a deciduate type intermediate in form between the zonary 

 and the discoidal. It does not conform exactly to Strahl's placenta 

 zono-discoidalis, and may be called placenta zono-discoidalis indistincta. 

 There is no decidua capsularis. 



Litter of Hybrid Dogs.f — R. R. Gates describes the progeny of a 

 thoroughbred Old English Bobtailed Sheep Dog (the mother) and a 

 thoroughbred Scotch Collie (the father). In no character was there 

 complete dominance of one parent in all the offspring. There was 

 remarkable diversity in the litter. There is a tendency as regards a 

 given character for the offspring to " take after " one parent or the 

 other, though in certain cases, as in the character of the hair, there is a 

 marked departure from either parent. This is, perhaps, the reappearance 

 of a character derived from some cross in the ancestry of one of the 

 breeds. 



b. Histology. 



Motor End-plate in Higher Vertebrates.^ — J. Boeke has made a 

 •comparative study of the structure and development of the motor end- 

 plate. He finds that the motor end-plate is not the real terminus of 

 the conducting element, which is only bound to the muscle by the 

 ■contact of " sole-plate." Very fine fibrils arise from the motor plate in 

 which the motor fibre attains a large surface in a system of neurofibrils. 

 These very fine fibrils enter into union with the contractile substance, 

 forming an extremely fine reticulum between the cross-striped myo- 

 fibrils. 



Musculature in Villi of Small Intestine.§ — A. Trautmann has 

 studied this in domestic animals. The origin of the musculature (of 

 the main mass at least) is in the muscularis mucosas, from which 

 muscle-fibres diverge and pass up between the glands into the propria 

 mucosae, forming a number of bundles up the villus. The bundles end 

 in connective tissue fibres, which end on the sub -epithelial membranes. 

 Perhaps some muscle fibres go directly to these. The muscle bundles 

 in the villus are surrounded by fine nets of delicate elastic fibres. 



* Bull. State Univ. Oklahoma, i. (1909) pp. 1-18 (3 figs.). 



+ Science, xxix. (1909) pp. 744-7. 



t Anat. Anzeig.. xxxv. (1909) pp. 193-226 (40 figs.). 



§ Op. cit., xxxiv. (1909) pp. 113-25 (1 pi.). 



April 20th, 1909 M 



