May 12, 1904] 



NATURE 



43 



quartzite and partly by intrusive sheets of diabase and 

 felsite. Their situation is, in the authors' opinion, associ- 

 ated with lines of weakness which have been set up by 

 the movements and dislocations which have affected the 

 Pretoria series in the diamond field area. In the case of 

 ihe Premier -Mine, the pipe is almost entirely surrounded by 

 a felsitic rock, which is intimately associated in places with 

 .1 diabase. This diabase and felsite, in fact, pass gradually 

 the one into the other, and form the lower and upper 

 portions respectively of a large intrusive spot. The walls 

 of the Premier pipe at lower levels, however, appear to 

 lonsist of th; quartzite which underlies this sheet. 



\\\ex\ plants spontaneous in the Transvaal, by Mr. Joseph 

 Hurtt-Davy. The author dealt with the question. Where 

 do our immigrant plants come from? An analysis shows 

 that the regions where the immigrants are native are 

 appro.ximately as follow-s : — the Mediterranean region (i.e. 

 the countries of south Europe, west .\sia, and North Africa, 

 immediately bordering the Mediterranean Sea), approxi- 

 mately 42 per cent. ; tropical Asia, appro.ximately 10 per 

 cent. ; tropical Africa, appro.ximately g per cent. ; tropical 

 America, approximately iS per cent. ; northern Europe, 

 approximately 7 per cent. ; South .\frica, approximately 6 

 per cent. ; temperate North America, approximately 3 per 

 rent. ; .Australia, approximately 3 per cent. ; temperate 

 "^outh .\merica, appro.ximately 2 per cent. ; Central .\sia, 

 approximately i per cent. The means by which plants 

 migrate from country to country were then considered. The 

 author said these fall under two heads : — (a) artificial means 

 or by the agency of man ; (b) natural means. The former 

 methods are responsible for far the largest part of modern 

 plant migration. They include (i) dispersal of roots and 

 seeds by farm machinery ; (2) conveyance of seeds and bulbs 

 in the earth around the roots of nursery stock ; (3) con- 

 veyance of seeds in the packing material of warehouse and 

 shop goods ; (4) conveyance in hay and other forage ; (5) 

 conveyance in impure samples of farm and garden seeds ; 

 (6) intentional introduction as useful or ornamental plants, 

 subsequently escaping the garden or farm and becoming 

 naturalised ; (7) conveyance from port to port in the ballast 

 of sailing vessels ; (8) conveyance in railway trucks, which 

 drop seeds at stations along the road ; (9) conveyance by 

 trek oxen and waggons, which drop them along the road- 

 side ; (10) conveyance along the tow-path; (11) conveyance 

 by irrigation water. 



The natural means are as follow : — (12) spreading by 

 runners as in the tweekgranesk ; (13) spreading by under- 

 ground rhejoines, as in Johnson grass or evergreen millet ; 

 (14I spreading by running roots, as in the Canada thistle ; 

 (15) special structures of the cupule, enabling it to throw 

 seeds for long distances ; (16) the provision of flying 

 apparatus attached to seeds, so that they are carried by the 

 wind — one of the most common methods; (17) drifting by 

 the wind over snow or frozen ground; (i8) tumbleweeds ; 

 (19) conveyance by floods and streams; (20) burr-weeds, &c., 

 carried in the hair and wool of animals, one of the most 

 common contri\'ances for distribution; (21) seeds and pieces 

 of plants carried on the feet of water-birds and aquatic 

 reptiles ; (22) kraal weeds, the seeds of which pass through 

 animals undigested ; (23) spiny fruits and branches carried 

 by animals. 



Trout acclimatisation in South Africa, by Mr. B. Bennion. 

 Trout acclimatisation was dealt with generally, and the 

 history of trout acclimatisation in South Africa — in Natal, 

 Cape Colony, and the Transvaal — Was given very fully. 



The science of bacteriology and its commercial aspects, 

 by Mr. \V. H. JoUyman. The object of this paper is largely 

 to answer the question, What practical results accrue from 

 the study of the science of bacteriology ? The reply is 

 divided into four sections, showing (i) the assistance the 

 science renders to medicine in the matter of diagnosis of 

 disease; (2) the improved treatment, and consequent 

 lessened mortality resulting from a knowledge of the causal 

 agents ; (3) the public health and sanitary science aspects 

 of the study ; (4) the work bacteria do in other than medical 

 fields. Towards the end of the paper Mr. Jollyman said, 

 the recent plague epidemic is testimony to the value of 

 bacteriological work ; what might have happened had not 

 the early cases been examined bacteriologically one cannot 

 tell, but it is quite certain that the value of an early diag- 

 nosis has been incalculable. With regard to the non- 



NO. 1802, VOL. 70] 



pathological side of the question, the remarks made about 

 brewing, butter-making, sewage disposal, soil fertility, &c. , 

 will suffice to indicate the commercial value of scientific 

 investigation into these branches. What is going to happen 

 in the future as the result of the study of bacteriology it 

 is impossible to foretell. On the medical side, men are 

 endeavouring to find out more about the causes of human 

 diseases, and to follow up these discoveries by the intro- 

 duction of specific cures. \'eterinary bacteriologists are 

 doing the same work for animals. 



In what may be called the bacteriology of the trades, 

 there is no question that there is a great deal to be done ; 

 brewing, tobacco-curing, manufacture of organic chemicals 

 — possibly glycerin — and soap manufacture may before long 

 become bacterial woi-k, and so on. In fact, the study of 

 these, the smallest living things known, leads to results of 

 the greatest commercial value. 



The bacteriological and other aspects of miners' phthisis, 

 by Dr. L. G. Irvine. Ihe author mentioned the urgent 

 matter of prevention of this disease, and, putting the ques- 

 tion as to why the disease should be more prevalent on the 

 Rand than in most other mining centres, he stated that 

 this was due to three reasons. First, the rock was hard 

 and the mines were dry ; second, the number of rock-drills 

 used was proportionately great ; and third, the quantity of 

 explosives used was also proportionately large. 



Notes on some pathogenic bacteria as found in the Trans- 

 vaal, and their variations from their European prototypes, 

 by .Mr. F. H. Joseph. 



Papers read before Section C. 



Survey practice in the Transvaal, by Mr. P. B. Osborn. 

 The author traced the development of survey practice in the 

 Transvaal from the time of the first crude subdivision of 

 land by the Voortrekkers to the present systematised scien- 

 tific methods. 



Geodetic surveying, by Mr. W. H. Greathead. The 

 author first defined geodetic surveying as the art of survey- 

 ing extended to large tracts of the earth's surface, in which 

 account must be taken of the curvature of the earth, and 

 proceeded to describe the delicate apparatus and methods 

 used in measuring base lines for the Natal and Cape Colony 

 survey ; also the apparatus for the Rhodesian survey. 



The mine surveyor and his work on the Witwatersrand, 

 by Mr. A. E. Payne. The present Government is pre- 

 paring, said the author, to establish the mine surveyor as 

 a professional man. The detailed knowledge of the great 

 variety of subjects coming within the scope of his work 

 is worthy of consideration. He should become the technical 

 adviser of the mine and be encouraged to develop his work 

 from the professional point of view of a mine surveyor. 



Fire protection in the mines, by Mr. G. H. Thurston. 

 The Rhodesian tick fever, by Dr. Theiler. Having first 

 pointed out the necessity for preventing the disease by wide 

 publication of the methods to be adopted and by legislation, 

 the author proceeded to discuss the geographical distribu- 

 tion and history of the malady. 



The bacterial purification of sewage, by Mr. F. S. 

 Prentice. .Some conditions respecting irrigation in the new 

 colonies, by Mr. W. Reid Bell. The blizzard of June 9-12, 

 1902, by Mr. C. M. Stewart, secretary. Meteorological Com- 

 mittee of Cape Colony. Seldom has South Africa been 

 visited by a snowstorm of such severity, duration, and so 

 extensive as that which started approximately at 6 p.m. on 

 the evening of June 9, 1902, and continued practically with- 

 out intermission at many places until the morning of June 

 12. Judging from the barometric readings, this storm 

 seems to have originated in an area of low pressure in the 

 centre of the colony, while the pressure in the west and 

 south was increasing rapidly. 



Papers read before Section D. 



The handling of young children, by Mr. P. A. Barnett. 

 The author pointed out that by people who recognised no 

 scientific basis for education there is a good deal of random 

 criticism of the efforts made to use systematically the data 

 provided by other sciences. We want more system — not 

 less ; though the science of education remains yet to be 

 formulated. 



A paper on special assessment was read by Mr. Stephen 

 Court. 



