578 SUMMARY OF CURRENT RESEARCHES RELATING TO 



that its function is to protect the larvae from ants and other enemies. It 

 is formed by the mingling of the fluid contents of the gut as they leave 

 the anus with bubbles of air from the last pair of stigmata. Breathing 

 appears to be carried on by the protrusion of the posterior end of the 

 abdomen from the froth, and the last pair of stigmata appear also to be 

 covered with a fatty substance which perhaps prevents the foam from 

 adhering to them. The secretion is slightly alkaline ; it appears to 

 consist of the sap of the food-plants after passing through the body, 

 together with secretion from the salivary glands, as is shown by the 

 presence of a trace of ptyalin. 



Mosquitos and Malaria.*— Dr. J. W. W. Stephens and Mr. S. E. 

 Christophers have investigated the distribution, habits, and breeding 

 places of Anopheles in Sierra Leone, in relation to the distribution of 

 malaria. They And that rock-pools, drains, and streams in Freetown 

 contain larvae at all seasons. Such larvae originate from parent Ano- 

 pheles found even during the dry season in dirty overcrowded houses and 

 among vegetation and refuse. Native houses, especially when crowded 

 and dirty, swarm with Anopheles, and form everywhere dangerous 

 sources of malarial infection. The immunity of natives from malaria 

 is not absolute, and natives attract mosquitos much more strongly than 

 Europeans. In the prevention of malaria, the important points are to 

 prevent the formation of stagnant pools by careful drainage, to exercise 

 strict personal precautions, and to destroy rank vegetation and dirty 

 huts. The source of greatest danger to travellers is the proximity of 

 huts in which native servants sleep. 



Alimentary Tract in Brachytrupes achatinns.f — L. Bordas shows 

 once again that there is great diversity in the alimentary tract in 

 Orthoptera ; for the details in the species named above differ from those 

 of Br. membranaceus, which the author has also studied. It is interesting 

 to notice that the alimentary canal in Br. acliatinus is more than twelve 

 times the length of the animal. Two facts are especially noteworthy: — 

 (1) The gizzard is provided with a strong internal chitinous armature 

 of six rows of pointed teeth (" a masticatory apparatus of the first order, 

 surpassing in efficiency that of all the other Orthoptera," or, rather, that 

 of all those carefully investigated). (2) The Malpighian tubes open 

 into a tubular bifid receptacle or bladder, which leads, by an unpaired 

 excretory duct or ureter, into the anterior portion of the hind-gut. 

 Histological details are summarised. 



Parental Care in a Beetle.:!:— Dr. J. E. V. Boas gives an interesting 

 account of the way in which Saperda populnea operates upon the sound 

 bark of Salix viminalis and Populus tremula, so that pathological 

 conditions are induced which afford sap£>y food for the young larvae. 



Plumules of Lycsena.§ — Dr. F. Koehler notes that the structures 

 called " plumules," " battledoor scales," or Duftschuppen, which occur as 

 secondary sexual characters in various Lepidoptera, have always aroused 

 much interest since their discovery in 1825, but that the question 



* Roy. Soc. Lond. Reports to Malaria Committee, 1899-1900, pp. 42-75 (3 maps). 



t Comptes Rendus, cxxxi. (1900) pp. 66-9. 



J Zool. Jabrb. (Abt. Syst), xiii. (1900) pp. 247-58 (1 pi. and 6 figs.). 



§ Tom. cit., pp. 105-24 (3 pis. and 6 figs.). 



