Julia Bell

A PEDIGREE OF MENTAL DEFECT SHOWING SEX-LINKAGE

THE following history of imbecility in eleven males of two generations was brought to our notice some years ago when a child aged.eighteen months, now indicated as V 54 on the adjoining pedigree chart, was brought to the outpatient department at the National Hospital by his mother who suspected that he was showing the signs of mental deficiency which she had already seen develop in some of the sons of her sisters; she was further aware of the condition in her cousins IV 13 and 14. The mother of the patient, IV 22, was intelligent and was much concerned about the family history; she provided at that time complete information regarding her own branch of the family and obtained the collaboration of her aunt, III 1, in working out the extended pedigree, including the three defective brothers V 16, 18, and 19. At this time one of us (J.P.M.) visited many of the descendants of III 4; he noted the undoubted intelligence of the seven daughters of III 4 and examined their defective sons in institutions or in their homes. More recently we have been able to get in touch with some of the descendants of III 2 and to see the three imbecile sons of IV 3. This side of the pedigree has been much extended since the original history was given by III 1, and to some extent modified. Our information was provided by IV 3 and 4, but they did not welcome inquiry and discouraged our attempt to see the only other living member of the sibship IV 1-11, or to call upon V 13. IV 3 was uncertain about some details regarding the sex and number of her nieces and nephews and we did not feel assured that she would know if, for example, IV 2, or IV 9 had had defective sons or grandsons. Two of the twins of IV 2 had died in infancy, but IV 3 did not know whether they had been boys or girls. It is illustrative of the secretive-ness of this branch of the family that at the time of the earlier pedigree III 1 was unaware that she had any grandchildren through her daughter IV 2, or that her son IV 1 had more than one child. IV 3 was fiercely protective in her attitude to her imbecile sons and resentful that, when found as small boys wandering in …

Linkage in Man

SINCE hæmophilia and colour-blindness are both sex-linked conditions, the genes determining them may be expected to show linkage. That is to say, if a hæmophilic is colour-blind the majority of his hæmophilic relatives should be colour-blind, and the majority of his non-hæmophilic relatives should not be so. Similarly, if a non-hæmophilic brother of a hæmophilic is colour-blind, a majority of his hæmophilic brothers and other relatives should not be colour-blind; a majority of his non-hæmophilic brothers should be colour-blind, while most of his sisters should be transmitters of hæmophilia or colour-blindness, but not of both or neither.

ON HOMOTYPOSIS AND ALLIED CHARACTERS IN EGGS OF THE COMMON TERN

(1) Origin of the material and method of measturement. The settlement of Common Terns, which provided material for the present work, is one of old establishment on Blakeney Point, Norfolk. This is a shingle spit of some 8 miles in length on the north coast of Norfolk, about 12 miles west of Cromer. The colony is situated on the very end of the point, with water on three sides. Here the spit is a combination of dunes, salt marsh aind shingle, and for the most part the nests are found on the openi shingle on the seaward side of the dunes. Nests are plentiful in the embryo dunes in some years, though this year (1913) none were found thiere. The colony was more scattered than usual and covered the greater part of a mile of sea front. To avoid missing any clutches, Miss K. M. Parker, B.Sc., and Mr William Rowan divided the nestinlg area into suitable well marked plots and worked these one after another. Each of these again were worked in strips, till a patch was completed, when the workers moved on to a remote one, to give the birds a chance of settling down again. After measurement each egg was numbered with indelible ink, so that any one egg was never measured twice. In all 20:3 clutches were handled.