THE L'UOGEESS OF SCIENCE. 



3«i 



nalunilly infest thorn. This determina- 

 tion has its practical as well as its 

 scientific value, for it enables us to 

 eliminate certain non-pat hojrenic para- 

 sitic organisms from the life cycle of 

 pathogenic organisms, stages of whicli 

 juay be found in mosquitoes. It further 

 has its direct practical bearing in that 

 the parasites of mosquitoes may multi- 

 ply to such an extent as to become 

 important factors in killing the insects, 

 or at least in rendering them less fer- 

 tile." 



He also refers to a similar Agam- 

 omermis, which he found in mosquitoes 

 in Leipzig and which, according to 



Paul Belloni du Chaillu, the African Ex- 

 plorer, WHO DIED ON April 29, liiOo. 



Leuckart, seems to have an influence 

 in decreasing the numbers of mosqui- 

 toes. Finally Dr. Stiles says : " These 

 cases represent interesting instances in 

 nature, where a pest is subject to other 

 pests which tend to hold the former in 

 check." 



We do not find in the article any 

 suggestion that the Public Health Ser- 

 vice is breeding these worms for prac- 

 tical purposes, as intimated by the 

 Sun, in order to kill mosquitoes. In 

 fact, it would take considerable study 

 to determine whether such a plan 

 would be practicable. If this parasite 



could be bred artificially in sufiicicnt 

 numbers it is by no means an imprac- 

 ticable proposition to utilize them to 

 destroy mosquitoes in regions where 

 the use of kerosene is dillicult or im- 

 possible. We do not, however, gather 

 from the article the impression that 

 the service projjoses any such jjlan at 

 present. In fact, we can see technical 

 difficulties in the way which would 

 make the method rather expensive, and 

 it would, at most, be applicable only 

 under certain conditions. We can not, 

 therefore, hold out any great hope that 

 Agamomermis culicis, which the New 

 York Sun has named the ' mosquito 

 destroyer,' presents to us at present a 

 substitute for kerosene and proper 

 drainage. But we share the view ex- 

 pressed in the original article that this 

 represents ' a case of parasitism of 

 considerable interest ' and that para- 

 sites of mosquitoes, like parasites of 

 other animals, ' may multiply to such 

 an extent as to become important fac- 

 tors in killing the insects, or at least 

 in rendering them less fertile.' 



RADIUM IN ENGLAND. 



That marvelous substance radium, 

 some account of which was published 

 in the Popular Science Monthly for 

 July, 1900, and June, 1903, still at- 

 tracts the attention of both men of 

 science and laymen throughout intel- 

 lectual nations. In London recently 

 the luminescent property of the rays 

 issuing from the element was shown to 

 King Edward and Queen Alexandra, on 

 the occasion of their visit to the Lon- 

 don Hospital, and the penetrating 

 power of the rays was also demon- 

 strated by the following: A pile of 

 six pennies was placed over a small 

 piece of radium and the light emitted 

 was visible through the coins. 



At the Museum of Natural History, 

 London, the director has arranged a 

 little exhibition with a view to giving 

 the public an opportunity of seeing the 

 material and some of its interesting 

 properties. Its source is shown in 



