The directional sensitivity of retinal rods.

Rod field sensitivity, 10-S(r) (i.e. the reciprocal of the radiance of a background required for 10-fold elevation of rod threshold) was measured for monochromatic backgrounds traversing the pupil at various points (r) on three subjects. The wave-length dependency of the directional sensitivities of the three foveal cone mechanisms of the principal subject have been reported previously (Alpern & Kitahara, 1983). Rods, as cones, are less sensitive to obliquely incident, than to normally incident backgrounds. At the pupil margin (4 mm) the effect is between 0.368 and 0.976 log10 units smaller for rods. After correction for losses by corneal reflexion and by absorption in the lens, S(r) for rods is reasonably described by the parabolic equation used by Stiles (1937) to quantify the directional sensitivity of cones. The small effect for rods precludes a description as consistently precise as this equation provides for cones. The steepness of the parabolic curve best fitting the directional sensitivity data of the rods of the principal subject was independent of background wave number. For a second subject, whose rods are supposed to be smaller, it was directly proportional to the square of that wave number. The latter is the expectation if the directional sensitivity of this subject's rods were determined by principles outlined in the diffraction theory of Simon (1970).

China and the one-child family. The one-child family in China: the need for psychosocial research.

PIP: China, with its very large base population, high rate of natural increase in the recent past, and very young age structure, is encouraging couples to have only 1 child in the hope that an average family size of 1.7 children can be achieved by 1980 and a population below 1.2 billion by the year 2000. According to the schedule, the proportion of fertile women giving birth to only 1 child would be about 50%, perhaps higher in urban areas. The government has begun educating the public through the news media and various organizations about the longterm implications of controlling population growth. Economic incentives given to couples having only 1 child include health care funds, free medical care, and free kindergarten and schooling. If the parents agree to have only 1 child they receive a bonus at the birth of the child and a monthly payment until the child reaches 14. Old age pensions, medical care, and living facilities for elderly 1-child parents are planned. 2 effective methods of encouraging the 1-child families are provision of honorary certificates to parents signing contracts to that affect, and the good example of the cadres. Despite a new marriage law, it will be some time before the traditional family structure can be changed to ensure that daughters have equal rights with sons and that a boy may marry into a girl's family. A survey conducted by the Beijing Normal University showed that only children tended to be superior to multiple children in intellectual development and in health. Results of comparative studies of personality and behavior of kindergarten age only children and other children have been conflicting. Further study is needed on the personalities of only children, and parents should be assisted in raising and educating their children to have desirable personality traits.^ieng

Parasites of the relict fauna of Ceylon. VI. More new helminths from amphibians and reptiles, a new host-record and redescription of Acanthocephalus serendibensis Crusz and Mills 1970.

A monogenetic trematode Polystoma hakgalense sp. nov. is described from the urinary bladder of the frog Rhacophorus cruciger eques, from the Hakgala Strict Natural Reserve (1 707 m). The following combination of characters distinguishes it fromm all other species of the genus: the random and reticulate anastomoses of the gut, the entire nature of the base of the opisthaptoral hooks, and the lack of vitellaria in the spaces between the opisthaptoral suckers. Acanthocephalus serendibensis is redescribed after a study of the original type specimens, and of fresh specimens from the horn-nosed lizard Ceratophora stoddarti from the Hakagala S.N.R. and from the gecko Cnemaspis kandianus kandianus from Haputale (1 418 m). The gecko is a new host record for A. serendibensis. The original description has been modified as regards the proboscis, which carries 10-12 longitudinal rows of hooks with 3-4 hooks in each row, the embryo within the egg, which bears minute spines over its body-surface and a row of hooks at one end, and the bursa of the male, which lacks bursal rays.

Parasites of the relict fauna of Ceylon. V. New species of nematodes from uropeltid snakes.

Two new species of nematodes have been found in endemic snakes of the family Uropeltidae which is restricted to montane regions in India and Sri Lanka. A trichostrongylid, Oswaldocruzia gansi sp. nov., is described from the small intestine of Rhinophis drummondhayi from Watawala (1 075 m) and the Namunukula area (1 200-1 300 m), R. philippinus from Pallatenne (618 m), and Uropeltis melanogaster from Kandy (800 + m). It is distinguished from other species of the genus chiefly by the trifurcate nature of the distal end of its dorsal ray and the number of terminal processes of each spicule. A cosmocercid, Aplectana uropeltidarum sp. nov., is described from the rectum of the same hosts as well as of Uropeltis phillipsi from Gammaduwa (720 m), and Rhinophis blythi from Talawakele (1 016 m). It was also found in the rectum of Teretrurus sanguineus from the Nalumukku Estate, Mandjolai (1 524 m) in S. India. It differs from all other species of the genus, especially in the number and arrangement of the caudal papillae of the male.