274 



NA TURE 



[January 22, 1903 



water containing a number of these larva? to rest on his 

 hand. In a few minutes, a slight irritation set in which 

 attracted his attention, but on examining his hand under 

 a lens he found that the larva had disappeared. His 

 conviction that they had forced their way through the 

 skin into the subcutaneous tissues was confirmed at a 

 later date, when he discovered that his intestine con- 

 tained the ova of the parasite and that he had thus in- 

 fected himself with ankylostomiasis. At the time, many 

 persons were inclined to doubt his explanation of the 

 occurrence, but he has since then made experiments 

 with dogs and human beings, and in each case has been 

 able to prove that the larvae, entering the body by the 

 skin, have worked their way into the intestine. 



His study of the Bilharzia parasite has not yet reached 

 the same stage of advancement, but although he cannot 

 at present demonstrate the fact, he is convinced that the 

 mode of infection is by the skin, as in the case of 

 ankylostomum, and not by the mouth, as has been sup- 

 posed. The negative evidence in support of this theory 

 is that if the larv.r of Bilharzia are brought even 

 momentarily into contact with weak solutions containing 

 acids they are at once killed, and this fact renders it 

 impossible for them to pass the stomach if they are 

 taken by the mouth. Positive evidence is still wanting, 

 owing to the great danger involved. 



Prof. Looss has not felt justified in making experiments 

 on human beings until a more perfect knowledge of the 

 larv.e is attained, and it is difficult to find animals with 

 a skin resembling that of human beings for the purposes 

 of experiment. But from some partial successes he has 

 had, he considers il only a matter of time before his con- 

 tention will be established, namely, that healthy persons 

 can become infected with bilharzia merely by dipping a 

 hand or foot into water containing larvae. When we 

 consider how much of their time the natives spend in 

 wading in the Nile and in the canals, the water of which 

 contains these parasites, we are at last within measur- 

 able distance of accounting for the extraordinary preva- 

 lence of the disease among them. 



THE VACCINATION ACTS. 

 'T"*HERE seems good reason to hope that the legal 

 ■*■ obligation of parents to procure the primary 

 vaccination of their children in infancy will be extended 

 in the ensuing session of Parliament so as to include 

 revaccination at about twelve years of age. The widely 

 representative and weighty deputation of the Imperial 

 Vaccination League which interviewed the President of 

 the Local Government Board last week made out a strong 

 case for this and other amendments of the present law 

 as to vaccination, and they had a most sympathetic 

 reception from Mr. Long. He, of course, spoke only for 

 himself, and not [for the Government as a whole, but 

 being the head of the Board which has charge of the 

 subject, and having evidently given it most careful con- 

 sideration and arrived at pretty definite conclusions as 

 to the main points requiring attention in a new Act, 

 there seems every reasonable prospect that these con- 

 clusions will be found embodied in a Bill and submitted 

 to Parliament in time for enactment before the session 

 ends. It must be recollected that the question comes up 

 this session in any case. The Act of 1898, which intro- 

 duced domiciliary vaccination and the Conscience Clause, 

 is only a temporary measure, ceasing to have effect after 

 the end of the present year. There is no chance of its 

 being allowed to drop so as to cause reversion to the old 

 system, and very little chance of its simply being included 

 in the Expiring Laws Continuance Bill. When they are 

 at it, therefore, it is important that Government should 

 deal with the matter with some degree of finality. The 

 five years' experiment has been most useful in furnishing 



NO 1734, VOL. 67] 



experience of the strong and weak points of the present 

 law, so that the whole subject is ripe for legislative 

 treatment. The aim should be to achieve, as nearly as 

 possible, German results by English methods, and the 

 chief points requiring attention are obligatory revaccin- 

 ation, the supply of glycerinated calf lymph, the adoption 

 of a standard of efficiency of vaccination, and the trans- 

 ference of the administration of the Vaccination Acts 

 from Boards of Guardians to public bodies better adapted 

 for the work. 



REi: DR. II. IV. WATSON, F.R.S. 



THE death, on January u, of the Rev. H. W. Watson, 

 Sc.D., F.R.S., has removed from the scientific world 

 a worker who did much to elucidate one of the most 

 difficult applications of mathematical reasoning to mole- 

 cular science. 



llenry William Watson was born in London in 

 February, 1S27, being the son of the late Thomas Wat- 

 son, of the Royal Navy. At the age of nineteen, he 

 gained the first mathematical scholarship at King's 

 College, London, and two years later obtained a 

 scholarship at Trinity College, Cambridge, where he 

 i graduated in 1850 as second wrangler and Smith's prize- 

 | man, Dr. Besant being senior wrangler. In 1851, he 

 was elected fellow and assistant tutor of Trinity College, 

 Cambridge, but on his marriage he was compelled by 

 the then existing statutes to seek a livelihood elsewhere, 

 and accordingly he obtained a mathematical mastership 

 at the City of London School in 1S54, and was appointed 

 mathematical lecturer at King's College, London, in 

 1856 and assistant master at Harrow School in 1857. 

 His work as a teacher ended after his appointment to 

 the rectory of Berkeswell, near Coventry, where he resided 

 until within a short time of his death. He was elected 

 Fellow of the Royal Society in 1S81. 



A considerable proportion of Dr. Watson's published 

 work was written with the collaboration of Mr. S. H. 

 Burbury, F.R.S. Among these joint writings, we notice 

 the treatise on generalised coordinates applied to the 

 kinetics of a material system, published in 1879, tne 

 article " Molecule " in the ninth edition of the " Encyclo- 

 pedia Britannica" and the treatise on the mathematical 

 theory of electricity and magnetism, of which the first 

 volume ("Electrostatics") appeared in 1SS5 and the 

 second in 1SS9. The appearance of the latier volume 

 occurred at a somewhat critical period in the history of 

 electromagnetism. It was Dr. Watson's hope to clear 

 up many of the obscure points in the deductive reasoning 

 on which Maxwell's theory of electromagnetism was 

 based. The same task had been undertaken about the 

 same time in Germany by Hertz, who had, however, 

 sought to substantiate the theory on experimental 

 grounds, and his demonstrations of electric oscillations, 

 followed up by the work of Fitzgerald and Lodge, 

 diverted attention from the mathematical treatment of 

 the subject. Dr. Watson, on the other hand, found in 

 the course of the work that many points in Maxwell's 

 theory could not be established by deductive reasoning 

 alone, but he has given remarkably elegant treatments 

 of many of the problems in which this difficulty does not 

 occur. 



The books written by Dr. Watson alone include a treatise 

 on geometry in Longmans' Text-books of Science Series 

 (1871), but his best-known work was the collection of 

 propositions on the kinetic theory of gases, which for 

 many years served as a text-book on this subject. While 

 the second edition of 1S94 was still in preparation, a con- 

 troversy arose as to the validity of the Boltzmann-Maxwell 

 law, and an apparent exception had been suggested in the 

 case of a system of lop-sided spheres. Dr. Watson, by 

 his investigation of the corresponding problem for circular 



