COCKROACHES, ETC. 145 



in rows, with their long axis vertical to the branch 

 on which the ootheca is built. The second secretion 

 is thinner in consistency, and as it pours out is beaten 

 up into a white foam or lather-like mass, by the very 

 rapid rotation of two small spatulate organs which are 

 protruded at the sides of the genital orifice. This 

 lather-like substance envelops the egg at the moment 

 of extrusion, so that the manner in which it is placed 

 in a position at right angles to that it occupies during 

 its exit from the oviduct cannot be made out. As 

 the eggs are placed in position the lather is constantly 

 being swept aside by the end of the abdomen until 

 it occupies a position on the outside of the ootheca, 

 which it entirely clothes throughout to a depth of 

 of an inch. Its function appears to be, in the first 

 place, to protect the egg from parasitic insects until 

 it is firmly placed in its matrix, and secondly, as an 

 outer covering to the ootheca, to shield its contents 

 from the direct rays of the sun and from the desiccating 

 effects of the hot air. The lather is full of air-bubbles, 

 and at first is sticky, adhering to the fingers like bird- 

 lime, gradually changing to a firm spongy consistency. 

 It is quite tasteless and free from odour. . . . The 

 ootheca is roughly square in section. The eggs are 

 arranged in a single layer, four abreast, and are usually 

 about forty in number. The viscid secretion which 

 forms the matrix of the case hardens with remarkable 

 rapidity, so that even a few seconds after the egg is 

 laid it is not possible to dislodge it with the point of 

 a knife. It may be that the lather-like secretion has 

 the function of protecting this fluid from the harden- 

 ing effects of the atmosphere while the egg is being 

 placed in position. 



11 



