December 21, 191 1] 



NATURE 



247 



ical stage formed an integral part of the instrument. 

 Now we find a "built in" mechanical stage in the 

 best Continental microscopes, and they, as instru- 

 ments of precision, are of a higher order than is 

 obtained in the English models. 



The fine adjustments in the Continental models are 

 made in a variety of patterns, but in their best form 

 we have as yet nothing in this country to compare 

 in quality of mechanism and slowness of motion. 



The mechanical draw-tube is provided in only a few 

 Continental models, a feature more common in the 

 English. Instead of this adjustment the Continental 

 makers provide the objective with correction collars 

 to allow of adjustment for varying thicknesses in 

 cover glasses, and this is considered more accurate 

 than the mechanical draw-tube. 



It is often claimed by English makers that one of 

 The advantages in possessing an English microscope 

 is that certain fittings are made to the Ro3'al Micro- 

 scopical Society's standard measurements. As re- 

 gards objectives and eyepieces there is little or no 

 difficulty in getting the products of all reputable 

 makers interchangeable, whether English or foreign ; 

 but a different state of affairs prevails in respect to 

 substage sleeves, for it is generally found that not 

 only does one English maker's condenser refuse to 

 fit into the substage of another, but it is a common 

 fault to find substage sleeves of English microscopes 

 varying so much in diameter that the ideal of R.M.S. 

 i.mdardisation has yet to be reached. 



Neither the society nor the makers have met the 

 needs of English microscopists in this respect, so it 

 may be left to the National Physical Laboratory to 

 >fep In and fill the gap, which is a wide one. 



Sprung fittings is another feature claimed for certain 

 f-lnglish models, yet a curious contrast is shown 



specting the durability of these adjustments as com- 

 , ared with the Continental. 



The screwdriver is a tool frequently used by owners 

 of the former class of instrument, while the leading 



ontinental instruments require adjustments only once 

 II many years of daily usage. 



Accordingly it would appear that fewer sprung 

 fittings add to the durability of the instrument. 



When choosing a microscope to embody the greatest 

 possible facilities for the present-day needs of the 

 serious worker, it will be found to be a product of one 

 of the best German houses. 



I 



SLEEPING SICKNESS AND BIG GAME. 

 N spite of the fact that a commission has been sent 

 out to Nyasaland to investigate the problem of 

 the relations of the big game to the spread of sleeping 

 sickness, under the direction of Sir David Bruce, the 

 most eminent authority on this subject in this or any 

 other country, persistent efforts continue to be made 

 to force the Colonial Office to prejudge the issue and 

 to cause the game to be exterminated before its 

 relation to the disease has been determined accurately. 

 The latest of these efforts was made in the House of 

 Commons on December 13, by Dr. Chappie, member 

 for Stirlingshire, who urged the Secretary for the 

 Colonies to relax the severity of the game laws so as 

 "to permit of the natives hunting game kno'ivn to 

 harbour the trypanosome in their blood in order that 

 both the game and the infecting fly which invariably 

 accompanied it might be driven off from the populous 

 centres." We have italicised two statements in Dr. 

 Chappie's speech, as reported in The Times of Decem- 

 ber 14, in order to direct attention to points in 

 which scientific knowledge at the present time does 

 not confirm, or is at variance with, the grounds on 

 which he bases his plea for extermination. His 

 NO. 2199, VOL. 88] 



argument is but another instance of the lamentable 

 ignorance of our legislators in scientific matters. 



The question under consideration has been discussed 

 at some length in the last three numbers of N.^ture, 

 and it will be sufficient here to summarise briefly the 

 present position of the problem. The extermination 

 of the game is urged by its advocates on the following 

 grounds : — (i) That antelopes and other wild animals 

 harbour Trypanosoma gatnbiense in their blood, and 

 are therefore dangerous as a source of infection ; (2) 

 that the tsetse-flies instrumental in the transmission 

 of sleeping sickness are dependent upon, and accom- 

 pany, the big game, and would disappear if the game 

 were destroyed. 



With regard to the first point, it has never yet been 

 shown that the big game, in a natural state, harbours 

 the trypanosome in its blood, but only that antelopes 

 can be infected with T. gambiense in the laboratory; 

 and this has been shown also for practically all the 

 cotnmon domestic animals. It may be left to common 

 sense to judge whether, in a region in which the 

 tsetse-flies abound, the domestic animals surrounding 

 the villages and homesteads, or the shy and timid 

 antelopes keeping their distance in the jungles, are 

 likely to be the greater danger to human beings as a 

 source of infection. 



With regard to the second point, those who are 

 acquainted with the tsetse-fly in its native haunts are 

 by no means agreed that it is dependent on big game, 

 or that it necessarily accompanies it; on the contrary, 

 many instances have been adduced of tsetse-flies 

 swarming in places where there is no big game of any 

 kind. If, however, it were admitted for the sake 

 of argument that the flies follow the big game, what 

 eftect is likely to be produced by the destruction of 

 their natural food? Is it to be supposed that the flies 

 would sit down and die helplessly of starvation? Is 

 it not far more likely that they would be attracted by 

 the food supply offered by the domestic animals sur- 

 rounding the homesteads, animals which almost with- 

 out exception are potential hosts of the trypanosome 

 just as much as the big game? If such an effect 

 were produced, the danger to human life might be 

 increased tenfold. 



The whole question is one beset with dangers and 

 difficulties, calling for full investigation of the complex 

 factors of the case and for the utmost caution before 

 proceeding to take action. To carry out the exter- 

 mination of the game in the present state of our 

 knowledge would be simply a leap in the dark, an 

 experiment which, so far as can be foreseen, would 

 lead to no amelioration of the conditions, but might, 

 on the contrary, be fraught with disastrous results. 

 The Colonial Secretary must be commended for having 

 refused, so far, to allow his hand fo be forced in the 

 matter. The wisest course in the circumstances is 

 surely to " wait and see " what are the conclusions 

 reached by Sir David Bruce's Commission. 



EXPLORATION IN THE DEPARTMENT OF 

 PET EN, GUATEMALA.' 



THE ruins of Tikal, completely hidden in the forest 

 in the northern part of Guatemala, distant 

 about thirty miles from the Lake of Peten, and forty 

 miles from the nearest habitation, are among the 

 most important and interesting in Central America. 



Since my second visit to these ruins in 1882, I have 

 been anxiously awaiting the result of further explora- 

 tions on this attractive site, and at last it has come 

 in a handsome volume published by the Peabody 



1 Memoirs of the Pe.ibody Museum of American Archaeology and Ethno- 

 logy, -HarvarH University. Vol. v., Nos. i and a:—" Kxploraiions in the 

 Department of Peien, Guatemala : Tikal," by Teobert Maler ; " Preliminary 

 Study of the Ruins of Tikal, Guatemala," by A. M. Toner. Pp. 135 + 28 

 plates+3 maps. (Cambridge, U.S A. : The Museum, igii.) 



