408 



a rich and brilliant deep blue colour. In the earlier stages they 

 were at first pale pink then became pale blue, darkening till they 

 appeared black, though showing deep blue under the microscope. 

 This coloring occurs not only in the cells of the bladder but also in 

 those of the valve. The Utricularia grows w r ith great rapidity in the 

 lake, and is a nuisance choking it up, but I do not think it is on the 

 whole a very objectionable plant, or that it seriously injures water 

 for human consumption unless it by any accident dies and putrifies 

 in large quantities. 



Chara sp. — Similar experiments were tried on a species of Chara 

 found growing abundantly in a ditch along the roadside at the edge 

 of the Botanic Gardens. It was thickly covered with red sand brought 

 down by the stream and Algae were also growing abundantly on it, 

 especially noticeable being a deep green Alga (apparently one of the 

 Cyanophyceae) growing in tufts. A quantity was collected and put 

 into tw r o jars with abundance of water. The water became very 

 cloudy. In one jar a pinch of copper sulphate was put. By next 

 day all the animal life seemed to be dead as were the Algae. The 

 Chara was apparently dying. The outer walls of the branches had 

 shrunk and the cell contents, chlorophyll granules, etc. had shrunk 

 into the middle. 



The proportion of copper sulphate given in this- case was really 

 larger than in the case of the Utricularia which perhaps accounted 

 for the more rapid effect. 



It is clear that copper sulphate has a strong effect on all these 

 plants and is also fatal to animal life in the water, but it is required 

 to be used in quantities too large to allow the water to be safely 

 used for human consumption afterwards. 



H. N. R. 



CORRESPONDENCE. 



ANTS ATTACKING RUBBER SEEDLINGS. 



Sapong Estate, 

 Fort Birch, 

 N. B. Borneo. 

 21 st October, 1906 



Dear Mr. Ridley, — May I ask your kind advice as to how best 

 to treat a new pest which is attacking our Para seed : this ant is best 

 known to Malays by its name of Semut Gatal because its bite pro- 

 duces the same swelling as does that of a mosquito, it is however 

 called by others Semut Krikit and Semut Gula. 



I have often seen it in houses where it frequently eats through the 

 corks of bottles containing oil. It also gets into hams, or eats into 

 biscuits or other sweet things. 



In many cases as soon as we have sown out a bed of Para seed 

 this ant covers each seed the same night with earth and then pro- 



