ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 173 



Children of all nationalities are less strongly pigmented than adnlts. In 

 some cases it is stronger in the part covered by the eyelids than in the 

 exposed part. 



The author raises two points as quite new. 1. Coloration of the 

 epithelial cells sometimes spreads as far as the junction of the limbus 

 and the cornea. 2. Chromatophores are constantly present in the propria. 

 Several variations of epithelial cells are found in the limbus, e.g. a 

 mucus membrane cell with modified columnar epithelium and epithelium 

 with goblet cells. The former was found in 2 '5 p.c. of 120 cases 

 investigated, the latter only in one case out of another series of fourteen. 



Swelling of the tunica propria of the limbus does not occur as 

 papillae but as ridges, which are most defined in the upper sites, while 

 they are missing from the temporal and nasal sites. The ridges are 

 arranged regularly, but differ in size with the case ; in forty-day-old 

 babies they are missing altogether. In the cell elements of the tunica 

 propria four kinds of cells must be distinguished : — Lymphocytes, 

 plasma cells, histiocytes and chromatophores. J. E. 



c. General. 



Avoidance of Objects by Bats in Flight. — H. Hartridge (Jouni. 

 Physiol., 1920, 54, 54-7). Bats flying at night, or in experimentally 

 produced darkness, avoid obstacles. It has been suggested that they 

 have very keen sight, but the capacity remains when eyes are covered. 

 It has been suggested that they have exquisite tactility, but they can 

 perceive objects at some distance away. " Bats in full flight and in what 

 appeared to be absolute darkness can not only steer round a room and 

 avoid one another, but they can also avoid obstacles such as threads. 

 Further they can tell whether a door is shut or open wide, or just 

 sufficiently wide open to allow them to pass." Bats have acute hearing, 

 and they emit short wave-length sounds near the audible limit of man, 

 and above that of some people. The hypothesis is advanced that their 

 flight is diverted by a specialized sense of hearing, since the sound 

 waves of short wave-length which they are known to emit are capable of 

 casting shadows and of forming " sound pictures." One may ask if 

 this would apply to the avoidance of threads. J. A. T. 



Susceptibility to Growth of Transplanted Tumour. — C. C. Little 

 {Joum. Exper. ZooL, 1920, 31, 307-26, 1 fig., 2 diagrams). Analysis 

 of certain factors underlying susceptibility and non-susceptibility of 

 mice to implants of a sarcoma of the Japanese waltzing mouse. The 

 factors underlying susceptibihty are definite inherited units, and certain 

 of them find their active expression as favourable agents in supporting 

 growth of the tumour implants in female animals, at the onset of sexual 

 maturity. J- A. T. 



Pulmonary Evolution in Mammals. — George S. Huntington- 

 {Amer. Joum. Anat., 1920, 27, 99-201, 15 figs.). The search for the 

 elusive hypothetical pro-mammalian ground-plan of bronchial architec- 

 ture has terminated somewhat like the hunt for the philosopher's stone. 

 The mechanistic concept of a definite and crystallized archeal bronchial 



