338 SECTIONAL TRANSACTIONS.— D. 



associated with the industrial labour supply. Hookworm appears to have been 

 introduced into Natal by imported Indian labour. In the Transvaal, native labourers 

 from Portuguese East Africa, where hookworm is endemic, form the chief source of 

 mine labour and are the present source of infection. As new batches of these native 

 labourers arrive weekly at the Witwatersrand gold mines, maintenance of infection is 

 assured under ordinary mining conditions, since supervision of every individual 

 native to ensure use of the proper latrines, and not promiscuous use of neighbouring 

 unoccupied or disused workings, is impossible. 



Natives rarely work a full year on a gold mine before returning to their kraals for 

 a long period. In most cases, six to nine months' mine work is usual. They often lose 

 their hookworms and other animal parasites after a short sojourn on the mines. 

 Infected natives from Portuguese East Africa are rather of the carrier than of the 

 suffering type, and rarely show obvious clinical symptoms. The presence of ova in 

 stools frequently can only be detected with difficulty by concentration methods. 

 Owing to soil contamination, hookworm has become established on a very small 

 number of the deep-level gold mines on the Witwatersrand, and a relatively small 

 number of white miners have contracted the disease. The use of large quantities of 

 water for laying dust in order to prevent silicosis, together with the heat of deep mines, 

 has produced conditions seemingly more favourable to hookworm than in the past. 

 Incidence of infection varies from mine to mine, depending on working conditions, 

 such as abundance of water and heat and newness or otherwise of sources of infection. 

 Hookworm has recently been declared an industrial disease. 



More native labour is needed on the mines. Mass treatment has been found im- 

 practicable on account of intercurrent disease conditions and concomitant helminthic 

 and protozoal infections, that may cause fatal sequelae. Mass examination of native 

 stools is not practicable under present conditions, even by concentration methods such 

 as are generally used. Examination of numerous mine soils by a modified Baermann 

 method from all working levels has shown infestation with first, second and third 

 stage larvae of hookworms. Nematode larvae from food-plants and larvae brought in 

 with water and from surface soil have to be differentiated in diagnosis from hookworm 

 larvae. Soils once contaminated may remain infected for long periods unless treated. 

 Common salt, as advocated manj' years ago by the late Dr. G. Turner, has been used 

 freely on the mines with good results, soils before treatment being heavily infested 

 with eggs and larvae but negative after application of salt. On one mine no white 

 case has occurred as a result of frequent soil examinations, energetic salt treatment of 

 positive sites and provision of new improved latrines in bad areas. Hookworm can 

 thus be controlled in industrial areas by stool examination and treatment of cases, 

 combined with the use of salt as a helminthic larvicide on soils. The danger of the 

 disease becoming endemic in Union Native Territories, through soil contamination by 

 infected natives returning from the mines, is possible but not very probable, since 

 sterilisation of faecal matter by solar heat and hot sand occurs fairly quickly. The 

 use of the bush near water for deposition of faecal matter is a far greater danger, as 

 the damper conditions there favour hookworm development. Education of native 

 and white man in hygienic principles is very necessary. 



Various treatments for hookworm disease have been employed, the most favoured 

 at present being carbon tetrachloride combined with oil of chenopodium. 



A demonstration of the various stages of the life-history of hookworms, of concen- 

 tration methods for detection of ova, and of isolation-culture methods for detecting 

 larvae in soils was given at the South African Institute for Medical Research. 



Dr. C. J. VAN DER HoRST. — Metamerism in the Enter opneusta. 



Among the many and mostly hazardous hypotheses put forward by Willey in hie 

 work on the Enteropneusta there is one to which I should like to draw attention. 

 Willey expresses his views in the following words : ' The gonads and gill-slits were 

 primarily unlimited in number and coextensive in distribution, the gonads having a 

 zonary disposition and the gill-sUts occupying the interzonal depressions.' Spengel 

 was opposed to this theory, as he was to all of Willey's theories and, in most cases, his 

 objections were justifiable. This German author expresses his opinion concerning 

 the metamerism of the Enteropneusta as follows : ' Solangewir unsnuran die nackten 

 Thatsachen halten, konnen wir nur festatellen, dass das segmentweise Auftreten der 

 Kiemen keinerlei Einfluss auf die iibrige Organisation hat.' And later on he writes : 

 ' Eine metamere Bildung der Gonaden zeigt sich in keiner Weise.' 



