ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 131 



cells have a strong tendency to cling to their own kind, and thus extend 

 in sheets, although under certain conditions active amoeboid movement 

 of isolated cells is also to be seen. In the majority of cultures move- 

 ment into the medium or along the endothelial surface (or both) takes 

 place according to the consistency of the culture medium. When serum 

 is used no migration of the culture into the medium takes place. Experi- 

 ments exclude chemotactic influences from the living tissue ; there may 

 be vigorous cell-movement on glass and celloidin films. Stereotropism 

 plays an important role in cell-movement. The behaviour of corneal 

 epithelium in vitro serves to throw some light on epithelial growth in 

 vivo,' for the experiments show cleai'ly that the epithelium is able to 

 extend fi'om the cut end quite rapidly in sheets into the medium (plasma), 

 or on the tissue (plasma and serum), and can cover a large area without 

 mitotic cell-divisions being necessary at all. J. A. T. 



Cell Movements in Corneal Epithelium.— Shinichi Matsumoto 

 {Jouni. Exper. Zool., 11)18, 27, 37-47, 4 figs.). Though the cornea of 

 the adult frog is thin and transparent enough for the observation of 

 epithelial movement, it is not an easy matter to note the details of the 

 process. But if the epithelium of the cornea be vitally stained with 

 neutral-red and Nile-blue characteristic granules are. seen in the cyto- 

 plasm. These exist through the entire period of cell activity, without 

 practically affecting the cells, and facilitate the study of cell movements. 

 Phagocytic phenomena of the corneal epithelium in reference to melanin 

 and carmin were definitely demonstrated. J. A. T. 



Minute Structure of Monkey's Pharynx.— Isaac Boetnowsky 

 {Ann. Sci. Nat. {Zool), 1919, 2, 175-98, 10 figs.). This is a study in 

 histology and specificity. A description is given of the epithelium of 

 the rhino-pharynx, the bucco-pharynx, the laryngo-pharynx, the larynx, 

 and the laryngeal sac in Cercopithems, and of the glands in the first four 

 of these regions, and of the associated adenolymphoid tissue. It. is 

 shown that the minute structure of the various regions in Cercopitheciis 

 nictitans differs from that in man, Theropithectis gelada, and chimpanzee. 



J. A. T. 



Structure and Origin of Dentary Enamel. — Ed. Retterer {G. R. 

 Soc. Biol. Paris, 1919, 82, 571-4). There is sometimes an enamel 

 organ, e.g. in armadillo, which. does not produce enamel, but the histo- 

 genesis shows that enamel never appears without being preceded by 

 ivory. The prisms of enamel arise not from epithelial cells, but from a 

 transformation of the peripheral ends of the rodlets of ivory. The pre- 

 dental organ of epithelial nature is a sine qua non of the formation of a 

 tooth. For although the epithelial cells do not furnish any part of the 

 tooth, they lend to the mesodermic cells which they cover and define a 

 •developmental capacity which they would not otherwise have. They 

 form an environment in which the mesoderm cells become odontoblasts, 

 and these odontoblasts produce both ivory and enamel. J. A. T. 



Cortex of Roots of Teeth.— Ed. Retterer {C. R. Soc. Biol. Paris, 

 1919, 82, 618-21). The root of the tooth has layers of ivory or den- 



