207 



Priestley (H.). The Value of various Chemicals as Mosquito 

 Larvicides. Australian Inst. Trop. Med. , TownsviUe, Queensland. 

 Half-Yearly Rept. from 1st July to 31st December 1916, p. 12. 

 [Received 6tli August 1918.] 



Experiments to determine the value of various chemicals as mosquito 

 larvicides have produced no results of practical importance, except 

 to show that the addition of very small quantities of sulphuric acid 

 increases the efficiency of potassium cyanide as a larvicide. It does 

 not seem possible to find any chemical or combination of chemicals 

 that will fulfil the requirements of being cheap, effective in concen- 

 tration, and relatively imiocuous to animals in the concentration 

 used and in the higher concentration that may result from evaporation 

 of the water. 



An apparatus for producing cresyl vapours for destroying adult 

 mosquitos has been investigated. It was foimd that vaporising 

 4 to ^ fluid oz. of cresyl per 1^ cub. yard of room space is sufficient 

 to kill all the mosquitos present if they are not in too well protected 

 places. The effect on mosquito larvae or pupae and on other insects 

 is not so good. The advantage of cresyl over sulphur dioxide for 

 fumigation is that the process is simpler and no injury is done to 

 the room. Experiments with this substance are to be continued. 



Cornwall (J. W.) & Menon (T. K.). A Contribution to the Study of 

 Kala-Azar (iv).— Indian Jl. Med. Research, Calcutta., v, no. 4, 

 April 1918, pp. 541-547. [Received 12th August 1918.] 



Having shown that the bed-bug camiot transmit kala-azar or 

 Oriental sore by its bite, since it is unable to regurgitate the contents 

 of its stomach in the act of feeding [see this Revieiv, Ser. B, vi, p. 1], 

 the authors have turned their attention to the contents of the rectum. 

 In cultures made with material obtained from the rectum of bugs 

 between 3 and 33 days after a feed of blood containing Leishmania 

 donovani, no growth of flagellates occurred. Tliis indicates that 

 even if a very few flagellates of L. donovani do survive the passage 

 from the stomach to the rectum, they lose their power of multiplication. 

 AVhen the rounded forms of L. donovani and of L. tropica enclosed 

 in leucocytes are transferred to certain nutrient media and maintained 

 at a temperature between 61° and 78° F., they develop fiagella, free 

 themselves from their enclosing cells and multiply profusely, this 

 multiplication contmuing until the nutriment is exhausted or until 

 inhibited by the products of metabolism. In a test-tube culture 

 the acme is reached after about 30 days ; degeneration then sets 

 in, scarcely any flagellates remaining alive after 60 days. If transferred 

 to a fresh tube before this stage is reached, multiplication begins 

 again. In the stomachs of bugs the culture tends to die out as time 

 goes on for reasons not apparently directly connected with the amount 

 of nutriment present. The hmit of survival that has been observed 

 is 29 days, though a second feed of blood will in some cases enable 

 the remaining flagellates to multiply further. 



Since the bug does not transmit flagellates in the act of biting, 

 and flagellates rarely, if ever, pass in the dejecta, the only apparent 

 ways in which Leishmania can be transmitted are by the rupture 



