EDITORIAL GLEANINGS. 357 
birds. There exists a large amount of evidence obtained from ob- 
servers, such as fruit-growers, gamekeepers, sportsmen, and others; 
and, although some of this may be and is useful, much of it has been 
distorted on its way through the prejudiced glasses of the observer. 
What is really necessary in order to obtain as accurate a conception as 
possible of the economic status of any species of bird is the actual 
dissection and recording of the contents of the crops and stomachs of 
a large number of individuals killed, not only in different months of 
the year but also in different localities, since different conditions 
exist in different regions, for example, in Kent and Lancashire. Such 
evidence is the only real and safe guide, and observational evidence, 
after careful selection, must only be taken as supplementary. Very 
little work of this nature has been accomplished in this country, but 
until it is done the regulations with regard to the protection of birds 
will be ever subject to the influence of the personal bias.and ignorance 
of the legislators, and such legislation will be on as equally a sound 
foundation as many of the fisheries regulations were until the advent 
of scientific fishery investigations. The Biological Survey Bureau of 
the United States Department of Agriculture furnishes an excellent 
example of the kind of work that should be carried out; it is collecting 
and publishing a valuable mass of information concerning the feeding 
habits of birds and their nestlings, from which, in the majority of 
cases, they are able to deduce the precise economic value of these 
birds. The Central Bureau for Ornithology of the Hungarian Depart- 
ment of Agriculture is doing similar work. It is proposed to form a 
British Economic Ornithological Committee, as such work can be best 
carried out by a number of biologists working together. At the last 
annual meeting of the Association of Economic Biologists, held in 
April, 1908, the author moved the following resolution, which was 
carried unanimously :—‘‘ That this Association, recognizing the great 
need of an organized inquiry into the feeding habits of the birds of 
the British Isles, with a view to obtaining a precise knowledge of 
their economic status, is of the opinion that a committee should be 
formed with the object of carrying on investigations on this subject.” 
The Board of Agriculture, recognizing the importance of the subject, 
have promised to help the inquiry. 
Mr. L. Doncaster discussed ‘Recent Work on Determination of 
Sex.” Until rather recent years there was the utmost diversity of 
opinion as to the determination of sex. Some regarded it as depend- 
ing on nutrition, others on the age of the parents or maturity of the 
germ-cells, some as depending wholly on the egg, and others, again, 
on the spermatozoon. Gradually, however, a certain amount of order 
has emerged from this chaos. In the first place, the facts of partheno- 
genesis made it clear that in many cases at least the sex was deter- 
mined irrevocably in the egg before segmentation; and the same 
thing was shown by such instances as Dinophilus and certain Mites, 
in which the eggs which will yield females are larger than those pro- 
ducing males, although both need fertilisation. The bee and those 
animals which behave similarly, on the other hand, indicate that sex 
may be modified by the spermatozoon, for in them virgin eggs yield 
males, fertilized eggs females; but here, again, no treatment after 
