The problem of the vector of Onchoccrca gibsoni was investigated in Kuala Lumpur, F.M.S., where the parasite is endemic and a high percentage of cattle is infected.

For reasons which are outlined, the experimental work was confined to species of Culicoides and Lasiohelea of which 18, possibly more, species were found on cattle, some of them being found to bite cattle in very large numbers daily.

The distribution of the microfilariae of 0. gibsoni in the skin of live cattle was found to be very irregular, even within small areas of skin. In transverse sections of skin the microfilariae appear to have a maximum concentration just under the epidermis at a depth of ·05 to ·2 mm.

0·52% of 1,523 Culicoides pungens, which were dissected soon after an infective blood meal, were found to have picked up the microfilariae. 0·96% of 1,670 of this species, dissected some days after an infective blood meal, were found to have developing or mature filarial larvae in the thorax or head. 0·35% of 3,734 of this species, were found to be naturally infected with filarial larvae in the thorax or head. The difference between the experimental infection rate and the natural infection rate is shown statistically to be significant and it is concluded that C. pungens is an intermediate host of O. gibsoni.

Culicoides oxystoma, C. shortti and C. orientalis were also dissected in large numbers and were found to pick up the microfilariae of O. gibsoni; in each of these species the experimental infection rate exceeded the natural infection rate, but the difference in none of these is significant. It is concluded however, from the results obtained and from the morphological similarity of the mature larvae found in these species with that in C. pungens, that these species are also intermediate hosts of O. gibsoni.

C. peregrinus and C. buckleyi are suspected but not proven intermediate hosts. C. anophelis and/or C. anophelisv. flavcscens and Lasiohelea stimulans were found to pick up the microfilariae but only partial development was found in them. C. sumatrae and C. raripalpis also picked up the microfilariae but no development was found in them. The remaining species worked with were entirely negative. In view, however, of the very minute percentage of infection which occurs in Culicoides spp. and the large numbers which must be dissected to obtain positive results, the negative results given by these less common species are not necessarily conclusive.

Fungi, which entrap and destroy small nematodes, have been known to mycologists for many years. Drcchsler, who, for a long time, has made a special study of these forms, has recently, in an important paper (1937), described and figured several species, including many new ones belonging to a number of different genera.

Amongst these fungi is one, Arthrobotrys oligospora Fresenius, which has long been known from the investigations of Zopf (1888) for its ability to capture, destroy and feed upon small free-living nematodes and also upon the larvae of Anguillulina tritici when supplied to it under experimental conditions.

The increasing mortality among domestic fowls in this country has of recent years drawn attention to the possibility that worms and other parasites may be factors in the causation of certain poultry diseases. Heavy infestations with worms are frequently observed on farms where mortality is high and although it is rare that death can be directly attributed to the parasites, it is thought that they might be responsible for loss of condition in the birds, and for lowering their resistance to disease. On the other hand, equally heavy infestations may be found in apparently healthy birds and the few experiments which have been carried out to test the pathogenicity of certain common intestinal worms have not shown any marked effect on the health of the birds as a result of the infestation. Further work along these lines is however, necessary before the pathogenicity of helminths in poultry and their relation to disease is understood.

There appears to be a common belief among veterinarians that liver-fluke infections, caused by Fasciola hepatica, are only transient and that if the animals do not succumb to the disease the parasites pass out of the body in about nine months' time. For instance, Mönnig's “Veterinary Helminthology and Entomology” states on p. 39: “The flukes (Fasciola hepalica) usually live about 9 months in the sheep and then die and pass out through the intestine.” Clunies Ross & Gordon, in their “Parasites of Sheep in Australia” (1936), say: “The majority of flukes probably die after about 9 months but some at least may survive for 2 years.” One might question on what scientific evidence these statements are based. Thomas (1881), discussing longevity, says with regard to one sheep examined: “The ewe had been kept under conditions which render re-infection highly improbable, and it follows, therefore, that the life of the liver-fluke may extend beyond one year”

Since 1935 a large number of chemicals including chloro-acetic acid and various water-soluble chloro-acetates, received from the Pest Control Committee of Imperial Chemical Industries, have been tested for their value in controlling the potato strain of Heterodera schachtii under the direction of Prof. R. T. Leiper, F.R.S.

Soils from Yorkshire and Ayrshire were used in the experiments, as they are of very different types, and might conceivably respond differently to chemical treatment.