The case of a 63-year-old severely mentally handicapped man is reported with chromosomal mosaicism. His karyotype was established as mosaic 46XY/47XXY with the fragile site present in a proportion of cells of both cell-lines. He showed phenotypic features which could be related both to the fragile-X and Klinefelter's syndromes.

Psychotic episodes and epilepsy can occur without mental retardation in tuberous sclerosis. The diagnosis may depend on elucidating the family history since physical signs may not be obvious. Establishing the diagnosis makes genetic counselling possible.

Three patients attempted suicide by burning in one ward of a psychiatric hospital in a period of less than 1 month. No such attempts had occurred there in the previous 9 years. The three patients were schizophrenics with depressive features who occupied the same room in the ward. It seems reasonable to suggest that at least the choice of method and the timing of these suicide attempts were influenced by imitation. Hospital staff should be especially aware of the influence of imitation in suicide in order to avert such undesired epidemics.

Bebbington (1986) draws attention to a possible cause for concern regarding the comparability of recent epidemiological research utilising the PSE-ID-CATEGO system of psychiatric caseness deter mination. In taking issue with our observation that cases in our recent community survey (Brown et al, 1985) were broadly similar in terms of severity to those reported in a recent series of out-patients (Sashidharan, 1985), he makes the point that such conclusions are only justifiable when it can be con fidently assumed that thresholds for symptom in clusion are applied uniformly between research centres. He argues that this assumption may well be invalid and marshalls two arguments to suggest that the Bedford team may have adopted less stringent rating thresholds. Firstly, he draws attention to the very different population prevalences of disorder reported in recent surveys, contrasting one-year prevalence figures for the Bedford College survey in Islington (Brown elal, 1985) withthelowerrates reported for other investigations in Edinburgh (Dean eta!, 1983) and Camberwell (Bebbington et al, 1981). Secondly, he reminds us of the body of evidence which suggests that psychiatrists operate stricter criteria for PSE symptoms than their lay colleagues (Wing et al, 1977a; Sturt et al, 1981).

Sociobiology was published in 1975. Four years earlier its author had published “an enormous and definitive book” on social insects, a work which established him as the world authority on that subject. In Sociobiology, Wilson set out to apply evolutionary theory to social behaviour not only in insects but throughout the animal kingdom. As a biologist he naturally included man among the animals, but it was this which caused the uproar. Had he omitted his last 33 pages-the chapter on “Man: from sociobiology to sociology” - his book would probably have led a quiet life as a well-written semipopular textbook on social animals.