THE RATE OF TRANSMISSION IN THE NERVE NET OF THE C?LENTERATES

Nerve net transmission in Metridium at 21°C. varies from 121 to 146 mm. per second.     

THE RELATIONS OF THE INDIVIDUAL AMPULL? OF THE SEMICIRCULAR CANALS TO THE INDIVIDUAL EYE MUSCLES : I. THE HORIZONTAL CANALS.

1. The reflex effect of direct mechanical stimulation of the exposed ampulla of the horizontal canal has been graphically recorded for each of the six extrinsic muscles of the eyeball. 2. Stimulation of a horizontal ampulla evokes a strong contraction of the homolateral rectus internus and of the contralateral rectus externus; at the same time the homolateral rectus externus and the contralateral rectus internus relax. 3. A single mechanical stimulus applied to the horizontal ampulla is sometimes followed by a nystagmus resulting from a series of rhythmic contractions of the externus and internus muscles. 4. Excitation of a horizontal ampulla gives rise to weak contractions of the superior and inferior recti and of the two oblique muscles of both eyes, simultaneously with the stronger contractions of the externus and internus respectively. 5. It is pointed out that the small simultaneous contractions of the four muscles just mentioned provide a virtual axis upon which the eyeball rotates. In other words these four act as fixation muscles. 6. It is suggested that some of the abnormal responses to horizontal rotation, seen in clinical cases, are due to the inaction of one or more of the fixation muscles.     

THE CHALLENGE OF THE “WELL CHILD”

Upon general practitioners and pediatricians falls the responsibility of recognizing and treating most emotional problems in young children. This may be best carried out by the anticipation of expected problems, and the advance guidance or counseling of parents. That such problems are of high incidence was indicated in experience at a pediatric clinic where approximately 40 per cent of 7,000 children observed had psychosomatic symptoms.In order to utilize effectively the limited time available in office practice for Well Child care, a physician must have at hand certain basic information on personality development. Many of the normal behavior patterns in children which frequently are misinterpreted as “behavior problems” by parents are presented herein in chart form, divided into critical age periods, to help physicians quickly recognize what is normal and what abnormal in various periods of maximal crisis. Most of the problems of conflict within a child and of conflict between parents and child, it is felt, could be and should be handled at the pediatric level. Some seriously disturbed children need to be referred for psychiatric care. When this is necessary, skillful preparation of the parent and the child by the family physician for referral is most important to successful psychotherapy.     

THE BREEDING STATUS OF THE CAPE VULTURE IN THE TRANSVAAL DURING 1980—1985

Benson, P. C., Tarboton, W. R., Allan, D. G. & Dobbs, J. C. 1990. The breeding status of the Cape Vulture in the Transvaal during 1980–1985. Ostrich 61: 134–142.

Ten of the 11 extant Cape Vulture Gyps coprotheres colonies in the Transvaal were censused using aerial and/or ground census techniques in the 1980–1985 breeding seasons. Minimum counts were obtained and best estimates of total numbers of “active nests” were determined using correction factors to compensate for incomplete photocoverage in the aerial technique and nest failures prior to the census dates. In 1985, the year when the most complete data were available, a minimum of 2741 and a best estimate of 2987 active nests were determined to be present in the Transvaal. At the large colonies, which were intensively monitored, breeding numbers did not fluctuate greatly from year to year, and it is thus estimated that about 3000 pairs of birds bred yearly in the Transvaal during the study period. Although the data indicate that the total numbers are greater than previously thought this is due to improved census techniques, rather than an increase in the population. Ninety-eight percent of breeding occurred at six colonies and 82% at three (Kransberg, Blouberg and Manutsa). The large colonies are associated with communal grazing (homelands) Private cattle and game farming and nature conservation areas, where the use of poison for predator control is minimal. The vulnerable status afforded the Cape Vulture in the South African Red Data Book—Birds (Brooke 1984) is justified because of the bird's disappearance from some breeding colonies, reduction in numbers at others and its vulnerability to poisoning.