July ist, 1887.] 



SCIENTIFIC NEWS. 



99 



of the algse on which many of them feed. It is, moreover, 

 supposed that those animals which sink and rise diurnally, 

 do so in order to travel over a greater range of feeding 

 ground, to find in fact fresh fields and pastures new. The 

 carnivorous lion of the desert feeds on the herbivorous 

 antelope, but the latter could not subsist, nor could the lion 

 exist, unless there were herbage for its victim to feed on. 

 In the same way there are carnivorous fishes, but the crea- 

 tures they live on could not subsist without the alg:e which 

 afford them nourishment. 



Photographs of Lightning. — The Council of the Royal 

 Meteorological Society are desirous of obtaining photographs 

 of Flashes of Lightning, as they believe that a great deal of 

 research on this subject can only be pursued by means 

 of the camera. Our readers are, therefore, requested to 

 give any assistance they can, either by sending copies of 

 any photographs of flashes of lightning which they may 

 already possess, or by endeavouring to procure some. It 

 may perhaps be well to mention that the photography of 

 lightning does not present any particular difficulties. If a 

 rapid plate and an ordinary rapid doublet with full aperture 

 be left uncovered at night during a thunderstorm for a 

 short time, flashes of lightning will, after development, be 

 found in some cases to have impressed themselves upon 

 the plate. The only difficulty is the uncertainty whether 

 any particular flash will happen to have been in the field of 

 view. The thunderstorm season is now approaching, and 

 doubtless many photographers will be found willing to take 

 up this interesting branch of their art. 



The Protection of Trees against Insects. — Not only 

 in this country, but in many others, the destructive effect of 

 insects on trees has long been a matter of serious concern. 

 This is especially the case in some of the leading cities of 

 the United States, where it is no uncommon event for a 

 large tree to be completely denuded of foliage in the course 

 of a season. So serious, in fact, has the matter become, 

 that the Government officials have taken it up, and Professor 

 C. V. Riley, the chief of the Bureau of Entomology, has 

 for some time given very close attention to it. We learn 

 from the Scientific American that in the first instance he was 

 led to examine the condition of the trees in the park and 

 grounds of the Capitol at Washington, and this brought 

 forcibly before him the fact that a problem of much impor- 

 tance had to be dealt with, because the trees in many other 

 places were exposed to similar influences. The results of 

 these inquiries are embodied in a pamphlet issued by the 

 United States Department of Agriculture, and its perusal 

 will well repay all who are interested in the subject. It 

 appears that when the English sparrow was imported, it 

 was hoped that the destruction of many of the tree insects 

 would begin, but the most injurious insects have not been 

 attacked. It is rather feared that the sparrow has favoured 

 the increase of these insects by driving away the native 

 birds who used to feed on them. 



Many plans have been tried for protecting the trees from 

 insects ; sometimes lime has been placed round the roots ; 

 sometimes the trunk has been scraped and whitewashed ; or 

 troughs filled with tar, or tarred ropes have been placed 

 round the trees. These methods have been only partially 

 successful, but according to Professor Riley, trees can now 

 be effectually rid of insects by syringing them with arsenic 

 compounds suspended in water. White arsenic or Paris 

 green may be used, but " London purple," a residue from 

 the manufacture of some of the coal-tar dyes, is recom- 

 mended as less liable to burn the leaves. Moreover, owing 

 to its colour, the trees which have been poisoned can then 

 be distinguished from those not treated, and this is important. 

 From one quarter to three-quarters of a pound is enough 

 for forty gallons of water ; the lesser quantity must not be 

 exceeded for young and delicate trees. With this it is best 

 to mix three quarts of cheap or damaged flour, as this 

 makes the poison adhere and reduces the liability of the 

 leaves to be burnt. Professor Riley recommends a good 

 spraying nozzle mounted on a rod connected by a hose 

 with a pump in the water barrel. Or if the process is to 

 be carried out on a small scale, a pail and a hand syringe 

 will be sufficient. During the operation, care must be 

 taken to agitate the water to prevent the powder from 

 settling to the bottom of the pail or barrel. It must not 

 be overlooked, however, that the arsenic compounds are 

 very poisonous, and great care must be taken to prevent 

 any going on to the person of the operator, as arsenic is 

 readily absorbed through the skin. 



The London School of Medicine for Women. — The 

 annual distribution of prizes took place on the 14th June. 

 We are pleased to find the Executive Council able to 

 state, in their official report, that this most useful institution 

 is progressing very satisfactorily. In fact, those who re- 

 member the up-hill work of establishing the school, and the 

 hundred and one battles which had to be fought against 

 real and fancied objections, find their most hopeful expecta- 

 tions more than realised. During the past winter session 

 twenty-two new students entered for medical study, and 

 there is now a total of no less than sixty-six attending the 

 school. Many of the past and present students have taken 

 distinguished honours in the London University and other 

 examinations, and Mrs. Garrett-Anderson, in her address 

 as Dean of the School, emphasized the fact that the 

 Council have taken the greatest care to insure the best con- 

 ceivable instruction, scientific and practical, being given to 

 those under their care. To say the least, it would be im- 

 politic for them to do otherwise, but it would be unjust to 

 suppose that this alone is their guiding principle : indeed 

 we know that it is not so. There are now fifty-two ladies 

 on the Medical Register, and as there is no lack of students 

 to follow in their steps, we may assume that there will be 

 no want of members for this new branch of the profession. 

 Let them do good work and true, and their success will be 

 assured, 



