Abstract: In the normal chick, conspicuous visual stimuli induce targetting and pecking together, with vocalization. All three are abolished by lesion of the intercollicular area (ICo) or of connections passing through its medial margin. After such lesions, chicks also cease to treat significant visual stimuli as if they were startling and exciting, and may delay response as a result. However, they are still able to recognise, orient accurately to, and respond appropriately to, a variety of complex visual stimuli (e.g. food grains, copulation object). In addition, they are little affected by strange surroundings. Lesion evidence suggests the mammalian subcollicular area to have similar functions to the ICo and to be homologous with it. A route (present in bird), which is well-known in mammals for its association with threat, defense and escape evoked by strange and frightening objects (amygdala-diencephalic periventricular system-central mesencephalic grey, A-DPS-CMG) is stimuli via the 2 ICo (subcollicular area). Two different mechanisms may be involved caudal to the ICo. One consists of tectal afferents which might modulate the evocation of targetting, pecking and other responses via the tectum. The other is the predorsal system of tectal efferents which may mediate such responses. Classical syndromes of tameness and unresponsiveness produced by various interruptions of the A-DPS-CMG route may depend on interruption of connections to these midbrain mechanisms. Attack is depressed by ICo lesions as one aspect of reduced responsiveness to conspicuous and startling visual stimuli. Avoidance, which is apparently mediated by a separate system, much as in Anura, is facilitated.

Abstract: Body weight of 48 horses competing in a 3-day event was measured the day before the event (baseline), following the dressage phase of the event (day 1), after the endurance phases of the event (day 2), and 18 to 24 hours after the endurance phases (day 3). Plasma sodium and potassium concentrations were measured the evening before, immediately after, and 10 minutes after the endurance phases. Total body water, water loss, and net exchangeable cation loss were then calculated. Body weight and total body water were significantly decreased, compared with baseline values, at all times during the event, and significant water loss was detected. The largest changes were recorded after the endurance phases of the event. Water deficits were still detected 18 to 24 hours after the endurance phases of the event. Mean plasma sodium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, and remained increased after the 10-minute recovery period, presumably because of dehydration. Mean plasma potassium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, but was not increased after the 10-minute recovery period.

Abstract: Details are given of a standard manner of recording breeding data of large mammals by game department officers, which is considered a great improvement on previous casual reporting. Information on the breeding in Northern Rhodesia of several ungulates and large Carnivora is summarised, and comparisons made with published data from other territories. It is stressed that much more study is needed, but certain points emerge from consideration of present information. Many species have their young at any time of year, and only a few have a really sharply defined birth season. The wart hog (Phacochoerus aethiopicus) seems markedly seasonal in the south of its range, but not in the northern parts. There is at present no data on the fluctuations in frequency of births among non-seasonal breeders. In the seasonally breeding species the actual birth months vary somewhat from north to south, and in the wildebeest (Connochaetes taurinus) there may be variation in the calving time due apparently to purely localdifferences of environment. The wild dog (Lycaon pictus) appears to be monoestrus, but data on the larger felids, though incomplete, seems to indicate that young may be born at any time of the year. Limiting factors in the study of breeding in African large mammals are pointed out, but it is suggested that further work on the lines of that carried out in Northern. Rhodesia would be profitable.