396 



KNOWLKDGK. 



OCTOHKR, 1012. 



typ<;s, the crystals assume a deaJ Mack color when they are 

 upon the lop of the film. 



In FiKtires 24>) and 430, nearly the whole of the action took 

 place on the surface, as the images seen throuKh the micro- 

 scope were black exceptini,' some portions at the edges which 

 were within the film and consequently of a brown color; this 

 dilTerence will be noticed in the illustrations. 



The chemical reduction prob.ably happens when the emulsion 

 dries, or soon afterwards, as the spots have been found in 

 paper of comparatively fresh make ; some paper has been 

 kept for a long period to ascertain if the action occurs or 

 increases with age. but neither feature was noticed. 



The unending variety of the designs and their minute 

 structure make them worthy of attention from all users of the 

 microscope. 



C. A. B. 



ORNITHOLOGY. 



By Wilfred M.\rk Webb. F.L.S. 



ORNITHOLOr.V .•\T THE HKITISH .^SSOCI.ATION. 

 — .Xt the British Association meeting, held at Dundee, a 

 considerable amount of interesting work on birds was recorded. 

 In the final report of the Committee dealing with secondary 

 sexual characters in birds [presented to Section D (/^oology)] 

 among other matters the cause of sterility in hybrids was 

 considered, and the following account was given : — .-Vn attempt 

 was made to rear hybrids between the common pheasant and 

 the jungle fowl, but the incubation of about sixty eggs resulted 

 in the hatching of a single chick, which died owing to a 

 cerebral hernia two days after hatching. This chick on 

 dissection proved to be a male, and the reproductive organs 

 were in a perfectly normal condition for a chick of that age, 

 showing no degenerative or retarded development. Three 

 hybrid male pigeons Ihybrid between domestic dove and 

 pigeon) were obtained from a pigeon-fancier. These birds 

 were kept for about a year and were paired with female 

 pigeons successfully, and the eggs were incubated in the 

 normal manner by both parents. In all cases the eggs 

 were sterile. The three hybrids were killed and dissected, and 

 their spermatozoa and testes, which on inspection appeared quite 

 normal, were examined histologically. On comparison with 

 normal doves and pigeons, it was found that the great majority 

 of the spermato;!oa of the hybrids were twice the normal si^e. 

 and this abnormality of size was traced to the fact that the 

 second maturation division was entirely suppressed. The 

 abnormality was traced further back to the first maturation 

 division, where it was found that the chromosomes, instead of 

 forming the ordinary eight synaptic groups, were irregularly 

 fragmented and scattered on the mitotic spindle, some of the 

 chromative masses being much smaller, others much larger. 

 than the normal synaptic chromosomes. Previous to this 

 division it appeared that the spermatogonia in the testes were 

 perfectly normal, so that we must ascribe the abnormality of 

 the spermatozoa, and the consetjuent sterility of the hybrids, 

 to the incapacity of the chromosomes derived from the two 

 parents to form synaptic pairs. These results will shortly 

 be published in detail in The Quarterly Jotirnitl of 

 Microscopical Science. 



Further observations on sterile hybrids are being made in 

 the case of some birds presented by Mrs. Haig Thomas, which 

 have been kept for varying times in aviaries and some of 

 which are still alive. Investigation of the sterile male shows 

 similar features to those observed in the case of the pigeon- 

 dove hybrids, but other observations on sterile females .and 

 another male hybrid are not complete. The sterile female 

 hybrids show a partial assumption of cock's plumage, and this 

 is probably correlated with the atrophy of the ovary. 



Another investigation was intended to discover if the 

 inheritance of spurs in the domestic hen could be explained on 

 the same lines as the inheritance of horns in horn-breeds of 

 ewe ; but the experiments have not been going on long enough 

 to speak with any certainty. 



Another experiment still in progress deals with the 

 inheritance of an extra toe in the fowl. 



Dr. C. J. Patton, who spent eight weeks at the Tuskar Light 



Station, County Wexford, smnmarised his remarks on bird 

 migration as follows: — In such a comprehensive study as the 

 migration of birds as carried out personally, over a consider- 

 able period of time, at an isolated rock on which a lighthouse 

 has been built, with a lantern of powerful illumination, so 

 many problems present themselves for investigation, and so 

 extensive and intricate are the statistics, that in order to cover 

 the groimd at my disposal I must here confine my remarks to 

 some special features in connection with my subject which I 

 hope will be of general interest. To the ornithologist of a 

 country, and especially in the case of a small one like Ireland, 

 where a complete knowledge of the avifauna is not so difficult 

 to acquire, one of the most fascinating objects is to wait and 

 watch for species which, either unknown or of very rare 

 occurrence in their natural habitat, are attracted and decoyed 

 by the luminous beams of the lantern under certain meteoro- 

 logical phases, when on passage. It is chiefly from the 

 lighthouse that so many birds new to Ireland have been 

 recorded, and during my visit I was enabled to add a few more 

 to the list. Another feature of considerable interest in dealing 

 with bird-migration presents itself at the Tuskar light-station, 

 namely : to what extent certain supposed desultory or mere 

 local migrants journey ? Several knotty points can, I am of 

 opinion, be disentangled as we study this subject at such an 

 excellent observatory as the Tuskar Rock. F"or any land birds 

 which appear, even when they alight and rest a few hours. 

 are bent on making a passage. No land birds could reside 

 here, where fresh water to drink is unavailable, food is very 

 scarce (for some species absent altogether), and the rock is 

 frequently wave-swept. The third and last feature 1 wish to 

 refer to is in connection with the study of variation. Splendid 

 opportunities present themselves, because such large numbers 

 of certain species fall victims by striking the lantern that these 

 can be collected and preserved with facility. 



A very useful discussion arose as the result of a paper 

 deaHng with the food of birds, which was communicated by 

 Professor J. Arthur Thomson. The details of the work are as 

 follows : — The inquiry was begun in October. 1909. under the 

 supervision of Professor Thomson, and with the valuable co- 

 operation of Professor Trail. The investigator, .Miss Laura 

 Florence, M.A., B.Sc, has examined about one thousand 

 eight hundred birds, chiefly from agricultural land in the 

 N.E. of Scotland. It is too early to draw many definite con- 

 clusions, but the inquiry shows the need for examining large 

 numbers from different areas, and throughout the year, if 

 trustworthy information is to be forthcoming as to the 

 injurious or beneficial activities of common birds. Many 

 current opinions on this subject rest on far too narrow a basis. 



Birds of ninety-five species have been examined, but large 

 numbers of any one species have not been procurable except 

 in a few cases, such as rooks and gulls. In some cases the 

 verdict given by previous investigators, such as Professor New- 

 stead, has been confirmed, e.g.. as to the injuriousness of 

 house-sparrow, wood-pigeon, and carrion-crow, and as to the 

 beneficial activity of hedge-sparrow, field fare, lapwing, and 

 plovers. On the other hand, there are several cases in which 

 the results up to the present do not altogether confirm previous 

 opinions; thus the diet of the black-headed gull and the 

 conunon gull shows a striking resemblance to that of the use- 

 ful lapwing. It is much to be desired that this inquiry, and 

 others like it elsewhere, should be continued for a term of 

 years ; and the cooperation of farmers and others interested 

 is solicited. 



The usefulness of the investigations was emphasised by 

 many speakers and an important point brought out was that 

 if the waste grain eaten by birds after the harvest had been 

 gathered in was not taken into consideration the balance 

 might in many cases be in their favour. The need also for 

 the making of investigations in many localities was brought 

 forward ; for a. bird which is injurious in one locality may not 

 be so in another. 



Mr. Lansborough Thomson described his method of bird 

 marking and gave some of the results, to which attention has 

 already been called in " Knowledge "; his paper also was 

 received with great cordiality and much counnendation. 



At the Conference of Delegates a short account illustrated 



