ig6 Indian Museum Notes. [Vol. V. 



In Figure I is seen a typical arrangement, vis., a little bolster- 

 shaped mass of mucous in vvhich the eggs appear to the naked eye 

 like little brown specks arranged in rings. About 20 eggs form one 

 ring, and as there are about 20 (estimated) of these rings, there will 

 be quite 400 eggs in one bolster. The part of the bolster which is 

 attached to the wall or weed is clear and contains no eggs. 



In specimens taken from the Norris Canal near the Principal 

 Civil Medical Officer's Office and, in fact, near any road, the mucous 

 is quite brown from the dust of the road. 



When a single egg is examined under a lower power of the 

 microscope, it is seen to be enclosed in a transparent chitinous shell 

 through which the development of the larva can be watched. 



A late stage of embryonic development is seen in Figure II (a 

 camera lucida drawing) where the eye spot and segments of the 

 future larvae can be distinctly seen. 



About 36 hours or more after deposition the eggs hatch and 

 produce larvae. 



This is brought about by the embryo making a rupture in the 

 chitinous shell and then wriggling its way out. Eggs, differently 

 magnified, showing the rupture, are to be seen in Figures III and IV, 

 both of which are camera lucida drawings. 



In Figure V a larva, half inside and half outside its shell, can be 

 seen. This figure is a microphotograph, and shows the character of 

 the burst shell, the larva, and the masses of algas, dirt, etc., in the 

 water in which the new-born larva is about to live. 



In the embryonic and the early larval stage these flies seem to 

 suffer much from the attacks of the larvae of other insects. 



The larvae are free-swimming, very active, and very voracious. 

 They rapidly grow in size, and in a few days appear much larger and 

 of a distinct bright red colour. 



On examining them under the microscope the red colour is found 

 to exist in little vessels, and, when examined by means of the 

 spectroscope, shows two absorption bands in exactly the same 

 position as those produced by the red colouring matter of human 

 arterial blood and which is called Oxyhemoglobin, 



By means of this Oxyhaemoglobin the larva is able to make use 

 of the air dissolved in water, and is therefore not compelled to be 

 constantly coming up to the surface of the water to breathe like the 

 larvae of Mosquitoes. 



As a consequence of this it is able to live in the mud at the 

 bottom of shallow parts of the lake or, if there is not natural mud 



