312 REPORTS ON THE STATE OF SCIENCE, ETC. 
greatly increased if the help which they are able to give to individual workers were 
more widely known. 
Your Committee has reason to believe that the Record Committee of the Zoological 
Society will welcome suggestions as to ways in which the Record might be improved, 
in the arrangement or selection of its materials or otherwise, so as to render it more 
useful to the working zoologist, and your Committee would be glad to receive and 
collate such suggestions from members of Section D and to forward them to the 
Zoological Society. 
Your Committee asks to be reappointed, with a renewal of the grant of 501. 
Parthenogenesis.—Report of Committee (Prof. A. MeEK, Chairman ; 
Mr. A. D. Peacock, Secretary; Dr. J. W. Hestop Harrison and 
Mr. R. BaGnatt). 
FurtuHer work on the parthenogenesis of saw-flies is reported as follows : 
The species Thrinax mixta KI. and T. maculata K1.—New work on the egg-laying, 
pupation, morphology and parthenogenesis of these species has been published in a 
paper, ‘The Biology of Thrinaxz mixta KI. and 7’. maculata K1.,’ in the ‘ Proceedings of 
the University of Durham Philosophical Society,’ Vol. 6, Pt. 5, 1923. 
Sex Ratios.—The sex ratios of the European parthenogenetic species, about 130, 
are being investigated, but, as the records concerning each species are scanty and 
scattered, progress necessarily is slow. The wide experience of the Rev. F. D. Morice, 
M.A., and Miss E. F, Chawner has been placed at the disposal of the secretary, and 
has proved of great value. It is hoped to publish results within the next year. 
Continuous thelytokous parthenogenetic reproduction in Allantus (Emphytus) pallipes 
Spin and Pristiphora pallipes Lep.—This is the fourth consecutive season for partheno- 
genetic strains of these species. Strains of the former have reproduced for eight 
successive generations, and of the latter for ten without resort to sexual methods. No 
weakening of the strains is perceptible. The former has never yet yielded a male among 
the 1,100 specimens,reared. 
Sexuality of Pristiphora pallipes.—A paper ‘ On the Males and an Intersex-Like 
Specimen of the Parthenogenetic Saw-fly Pristiphora pallipes Lep.’ has been pub- 
lished in the ‘ British Journal of Experimental Biology,’ Vol. 1, April 1924. In it, 
the morphology of the rare males and an intersex-like specimen are discussed from 
specimens(2¢.¢ and 1 $) obtained under special experimental conditions where the eggs, 
during maturation, were immersed in a solution of magnesium sulphate (0-2 per cent.). 
Repeat experiments to ascertain the possible rdle of this chemical as a sex-changing 
agent, so far, have yielded negative results, but a number of experiments are still not 
concluded. 
A third male was obtained on April 15, 1924, from a batch of eggs subjected, during 
maturation, to immersion in water of temperature 38-29 C.>17:59 C. Repeat experi- 
ments are in progress. 
The sexual behaviour of the females and the rare males has been studied. The 
females are a-dechandrous, i.e. refuse the males, but proceed to lay. One pairing, how- 
ever, was effected, and from the nineteen offspring reared to pupz, seventeen imagines 
have emerged, all females. (See summary under Section D of this year’s programme.) 
Publication will take place in the ‘ Brit. Journ. Exp. Biol.’ 
Sex-change experiments.—Attempts to influence the sex of the female-producing 
Allantus (Emphytus) pallipes by subjecting eggs during maturation to physical and 
chemical agents have yielded negative results. Agents used include uranium oxide, 
X-rays, ultra-violet light, electric fields, manganese chloride and magnesium sulphate. 
Pteronidea(Nematus)ribesit Scop.—Experiments on the parthenogenetic conditions 
existing in this species continue, and it is hoped soon to correlate these with cytological 
observations from new material, and from that of the late Professor L. Doncaster, 
whose preparations, through the kindness of Professor J. Stanley Gardiner, have been 
placed at the disposal of the secretary. 
Gametogenesis.—A large amount of material from several species has been read, 
and papers are in preparation. In this connection, the discovery may be announced 
here of 1, nurse cells in the male gonad, and 2, large accessory nuclei which cluster 
around the nucleus of the egg growing in the ovariole of Platycampus luridiventris 
Fall. ; these resemble those found by Buchner in many other hymenoptera, but not 
observed by him in many species of saw-flies which he examined. 
Pathology.—A myxosporidian (?) parasite has been discovered in the gonads of 
Thrinax sp. and is being studied. 
