TRANSFORMATIONS OF BUFFALO GNATS. 11 



schense Fab.), is probably erroneous, as the species is very like S. 

 venustum in size and structure. It is the opinion of the writer, 

 from many observations, that the largest possible number of eggs 

 which are deposited at one time by a single female can not exceed 

 500. 



The question whether eggs of Simulium can be subjected to desic- 

 cation and then hatch after being immersed again in water is of 

 interest, as it has been suggested that in the more or less torrential 

 streams found in Texas and the Western States, which flow only a 

 few months in the year, the eggs might remain in a dry condition 

 during the summer and hatch in the fall or spring with the rising 

 of the water. For this reason experiments have been made by the 

 writer to ascertain whether Simulium eggs, after partial or complete 

 desiccation, would hatch on being again placed in water, as is the 

 case with some species of mosquitoes. These experiments all showed 

 that at Spartanburg, S. C, the contents of freshly laid eggs became 

 completely disintegrated after being thoroughly dried, and that when 

 the eggs contained embryos, the latter became distorted on the second 

 day after removal from the water, and though they were replaced 

 in running water after that period the contents of all finally disinte- 

 grated without a single egg hatching. 



When eggs are found at any distance above the water line, the 

 writer believes, investigation will show that a fall in the water level 

 has occurred. The great outbreaks of Simulium in the large rivers 

 during the early spring are due primarily to the fact that the rising 

 water submerges the growth on the banks and that the water either 

 rises or remains at the same level throughout that period, thus pre- 

 venting desiccation of the eggs. 



THE EGG STAGE. 



The eggs of Simulium are usually rather triangular in shape, with 

 the angles broadly rounded. (PI. Ill, figs. 1-5.) The egg of S. 

 pictipes (PI. Ill, fig. 6) , however, is more ovoid in shape than that of 

 the four other species dealt with in this paper. The shell, which is 

 very tough and apparently somewhat chitinous, withstands the action 

 of the water for a considerable period without disintegrating, and 

 has been found by the writer in a good state of preservation after 

 six weeks in this element. 



The color of the egg when first laid (PL III, fig. 1) is opaque white, 

 which changes to yellowish brown as the development of the embryo 

 proceeds. The interior of the newly laid egg appears to be an even 

 mass of yolk substance. When the egg contains a half-developed 

 embryo the yolk substance seems to be consolidated into a central 

 mass, indented at both extremities and surrounded by layers of 



