OCIMUM 415 



by the insects, which seemed "to be actually invigorated by the apparently 

 stimulating effect of their new quarters." 



The Sergents, in Algeria, experimented both with the castor oil plant {Ricinus 

 communis) and with papaya or pawpaw {Carica papaya) on account of the 

 reputation that these plants had as deterrents against mosquitoes. A pawpaw 

 about 90 cm. high and in good condition was enclosed in a mosquito bar of tulle, 

 oblong in form, with its axis directed perpendicularly to the window from which 

 the light came. In the end of the bar nearest the window they suspended a 

 raisin grape, as food for the mosquitoes, and a little vessel of water. Then at 

 the opposite end of the bar they put in four females of Anopheles macuUpennis 

 and four females of Culex pipiens. They wished to see if the instinct which 

 attracts the mosquitoes toward the light and towards an apparent way of escap- 

 ing, and on the other hand the need of nourishment and water, would induce the 

 mosquitoes to pass the middle portion of the bar which was entirely filled with 

 large leaves of the pawpaw. At the end of four minutes one Anopheles and one 

 Culex had passed from one end of the bar to the other ; at the end of ten minutes 

 another Anopheles and two Culex were seen to alight upon the pawpaw leaves 

 and they remained there many hours. The mosquito bar was left in place for 

 eight days. During this period the mosquitoes moved about freely and rested 

 frequently upon the leaves and branches, sometimes for hours. 



An experiment exactly similar was carried on at the same time with Ricinus 

 communis, with the same results. When these experiments were concluded at 

 the end of eight days one Anopheles and one Culex were found dead in the paw- 

 paw mosquito bar, and in the Ricinus bar also one Anopheles and one Culex. 

 But in similar cages in another room during the same time with Carica and 

 Ricinus plants absent, six Anopheles out of twenty had died, and nine Culex 

 out of twenty-eight. The authors concluded that pawpaw and castor oil plants 

 are powerless against mosquitoes. 



OCIMUM. 



Another plant which is said to act as a deterrent is a lavender known as Oci- 

 mum viride, a perennial which grows from 3 t-o 6 feet in height and occurs from 

 Senegambia southwards to Angola. Mr. A. E. Shipley in the Tropical Agri- 

 culturist of February 2, 1903, pp. 555-556, states that Major Burdon, resident 

 of the Nupe Province, northern Nigeria, had given him the following account 

 of the plant : 



" A fragment of what turns out to be Ocimum viride was given me in August 

 last at Lokoja, ISTorthem Nigeria, by Capt. H. D. Larytnore, C. M. G., E. A., 

 Resident of the Kabba Province. Capt. Larymore's notice had been drawn to the 

 plant by a native living in a low-lying part of the native town at Lokoja, who had 

 told him that the natives suffered very little from the swarms of mosquitoes 

 which existed in that part, as they protected themselves from them by the use of 

 this plant. 



" Capt. Larymore made inquiries and obtained a few specimens of the plant, 

 which grows wild, though not very abundantly, in the neighbourhood of Lokoja. 

 These specimens he planted in pots and boxes and kept in and about his house. 

 The specimens I saw were about the size of a geranium. 



