DI2 ECONOxMIC VALUE OF ODONATA. 



tingham Road, the Natal streams full of dragon-flies are sparsely 

 inhabited by fish. 



The time is not yet ripe for any attempt at a definite evalua- 

 tion of the economic work of our African dragon-flies. What 

 evidence is at hand points to their playing no economic role at 

 all as adults, but possibly a fairly extensive one of both benefit and 

 iiarm as nymphs. 



DRUG TREATMENT IN NUTTALLIOSIS OF EQUINES. 



By GiLLEs VAN DE Wall de Kock. M.R.C.V.S. 



(Not printed.) 



BOVINE CONTAGIOUS ABORTION IN SOUTH 



AFRICA. 



By Eric Maxwell Robinson, M.R.C.V.S. 

 (Not printed.) 



ON CERTAIN CHANGES IN THE EXTERNAL SEX- 

 CHARACTERS OF OSTRICHES, OCCURRING 

 AFTER REMOVAL OF THE REPRODUCTIVE 

 GLANDS. 



Bv Sir Arnold Theiler. K.C.M.G., D.Sc, and 

 D. Kehoe, M.R.C.V.S. 



(Not printed.) 



SPECTROGRAPHY OF SEAVTEED AsHES. — E. Cornec, 



in Coniptes rcndus,'^" gives an account of a spectrographic study of 

 the ashes of certain marine ])lants. In Laminaria ash, silver, 

 arsenic, cobalt, copper, manganese, nickel, lead, zinc, bismuth, 

 tin, gallium, molybdenum, gold, antimony, germanium, glucinum, 

 titanium, tungsten, and vanadium were found, the occurrence of 

 the last six not having been previously reported either in sea 

 water or in marine plants. Only spectrographic traces of gold, 

 bismuth, gallium, and germanium w6re observed. 



*168. 513-514 (1919)- 



