290 



NATURE 



[June 13, 1918 



results to British surgeons, and convinced them that 

 this new departure in surgery deserves their most 

 favourable consideration. The muscles of the stumps 

 are yoked to artificial levers by various devices, and 

 rt is surprising how the parts become tolerant of the 

 abnormal burdens placed on them by the surgeon. 

 The patient is even able to estimate the weight of the 

 load which he attempts to lift. For success the 

 surgeon depends on the intelligence and perseverance 

 of his patients as much as on his own technical 

 skill. It would be wrong to give rise to the hope that 

 " kineplastic " surgery can ever give a limbless man 

 conditions of movement comparable to those he has 

 lost, but this new departure in surgery does promise 

 an amelioration of our former helpless outlook. Prof. 

 Putti has presented models and casts of " kine- 

 matised stumps " to the museum of the Royal College 

 of Surgeons of England. 



.\PPRECIATIVE notices of the work of Mr. C. D. 

 Ahrens, who died on March 14, at eighty-one years of 

 age, are contributed to the Journal of the Quekett 

 Microscopical Club by Mr. E. M. Nelson and Prof. 

 F. J. Cheshire. We extract the following particulars 

 from Mr. Nelson's notice : — Mr. Ahrens was a prism 

 and spar slitter. He made Nicol prisms and analysers, 

 quartz and calcite prisms of all kinds, as well as the 

 glass prisms for Wenham binoculars. In 1867 he 

 designed a binocular upon quite a novel plan. The 

 rays . issuing from the back of the objective were 

 separated to an angle of 15° by a double-image calcite 

 prism ; these rays were then crossed over by two flint 

 prisms, to correct the chromatic dispersion. The rays 

 used were the extraordinary, the ordinary being 

 diverted out of the path. The tubes were equally in- 

 clined to each other. In 18*1 he introduced another 

 new binocular, in form like Stephenson's. It had 

 parallel tubes, but they were bent as in the Stephen- 

 son. The ingenious part of the arrangement was 

 that the beam from the back of the objective was 

 divided by two Wollaston camera-lucida prisms placed 

 back to back ; these deflected the rays right and left, 

 then another prism with two reflections bent them up 

 the tubes. Probably a carefully made binocular on 

 this plan would be a very successful instrument. In 

 1884 he designed a bent-tube erecting monocular micro- 

 scope; obviously a most useful instrument, it is sur- 

 prising that some energetic manufacturer has not taken 

 up this idea. In the same year Mr. Ahrens designed 

 a new polarising prism, which was further improved 

 by Mr. H. G. Madan in 1885. In 1886 he brought 

 out yet another improved form of polarising prism, the 

 object of which was to lessen the ratio of its length 

 to its breadth. That of the Nicol is about 3:1, while 

 the Ahrens was I5 : i. In 1887 he made an erecting 

 microscope the design of which has had far-reaching 

 consequences. The erection was obtained by Porro 

 prisms. It was Ahrens who first brought the long- 

 forgotten Porroprism to remembrance. 



We have received the Report of the Bacteriologist, 

 State Board of Agriculture, Michigan, for the year 

 ended June 30, 19 17. Much work has been done on 

 contagious abortion of cows. Vaccines prepared with 

 the Bacillus abortus did not prevent infection with 

 succeeding abortion in guinea-pigs. The bacillus soon 

 dies out on wool, silk, and in soil ; on the two former 

 materials within a fortnight, and in soil within a 

 week. Cultivations of leguminous bacteria have been 

 tested as fertilisers for leguminous crops. On alfalfa 

 they seem to be of benefit in about one-third of the 

 crops treated, but on other crops no definite conclusion 

 has yet been reached. 



" The Report of the Departmental Committee ap- 

 pointed to inquire as to precautions for preventing the 

 NO. 2537, VOL. lOl] 



danger of infection by anthrax in the manipulation of 

 wool, goat-hair, and camel-hair has just been issued. 

 (Cd. 9057). The Disinfection Sub-Committee concludes 

 that anthrax can only be prevented either by preventing 

 the disease among animals or by the destruction of 

 the organisms in the wool or hair. The Sub-Com- 

 mittee has devised a process for the last-named pur- 

 pose, the essential features of which are :— (i) Tre^at- 

 ment of the material with a warm aqueous solution 

 of soap containing a little alkali, followed by squeez- 

 ing between rollers ; this disintegrates the blood-clots. 

 (2) Treatment with a warm solution of formaldehyde 

 in wateir and again squeezing; this destroys most of 

 the spores. (3) Drying and standing for a short time, 

 by which any remaining spores are killed. The Com- 

 mittee is of opinion that the Government should 

 undertake the work of disinfection at a central institute 

 or station. For the treatment of 10,000,000 lb. of 

 wool annually the cost of the central station is esti- 

 mated to be i8,oooZ., and the working cost to be from 

 0-544^. to 0-824^. per lb. of untreated material. These 

 figures were computed at pre-war prices, and about 

 75 per cent, would have to be added to meet present- 

 day conditions. 



CAPf; E. G. Fenton discusses in the May issue of 

 Man the remarkable cart-ruts found in Malta. It has 

 been formerly assumed that they date from prehistoric 

 times, and that they probably belong to the Neolithic 

 period. There is no sign of a groove cut by horses' 

 feet' between the ruts,, and the suggestion has been 

 made that they are the result of human power in the 

 shape of a number of men drawing waggons, and 

 that the Neolithic civilisation was brought to a close 

 by a period of desiccation, such as that discussed by 

 Ellsworth Huntingdon in "The Pulse of Asia," the 

 dawn of our Mediterranean historical period being 

 heralded by the increase of moisture. Capt. Fenton, 

 on the whole, believes that they date from the early 

 part of the Iron age, at a time when the Mediter- 

 ranean was moister and the island was capable of 

 supporting a larger population than under present 

 conditions. The suggestion that these climatic 

 changes can be equated with events in Egyptian his- 

 tory is interesting, but the evidence is scarcely 

 sufficient to support any definite conclusion. Prof. 

 Boyd Dawkins. in the June issue of Man, asserts 

 that the ruts are "due to the weathering of the rock 

 under vaporal conditions. They are merely the 

 ordinary joints, widened and eroded by the rain- 

 water containing carbon dioxide, familiar to geologists 

 in all limestone plateaux, and to be seen over very 

 wide regions in Southern France." 



A RESEARCH of interest to veterinarians and zoologists 

 on the efficiency of some Anthelmintics has been pub- 

 lished by M. C. Hall and W. D. Foster {Joum. Agric. 

 Research, vol. xii., No. 7, 1918). By comparing the 

 number of worms evacuated after the administration 

 of various drugs with those found in the digestive 

 tracts of "patients" killed a few days later a sort of 

 "percentage efficiency" can be calculated. The 

 number of experiments, of this kind is necessarily 

 limited, but the result in nearly all cases is disappoint- 

 ingly low. Dr. H. E. Cross has been trying the effect 

 of various emulsions intended to protect camels from 

 the attacks of blood-sucking flies (Bull. 76, Agric. 

 Research Inst., Pusa) ; he finds that the only service- 

 able agent is castor-oil, which is too expensive for 

 practical use. 



A SYSTEMATIC zoological paper of more than usual 

 interest is Mr. J. Hewitt's ' Survey of the Scorpion 

 Fauna of South Africa," which constitutes part ii. of 

 the Transactions of the Royal Society of South Africa 

 (vol. vi., 1918). The region has a large number of 



