the Life History of Gongylns gongyloides. 131 



eggs arc arranged in a single layer, four abreast, and arc 

 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 hardening effects of the 

 atmosphere while the egg is being placed in position. 



It may further be noticed that the female uses her cerci 

 Avhich are attached to the last ventral segment, in the 

 manner of a pair of callipers to shape her egg-case and to 

 arrange the lather-like substance in regular parallel rows 

 along its exterior, corresponding in position to some degree, 

 with the rows of eggs within. 



The ootheca is finished off at either end with a sort of 

 rostrum formed by a vertical plane of matrix substance 

 projecting in the middle line of the structure. That formed 

 at the commencement of the construction is short and 

 rounded, while that formed at the end of the process is 

 drawn out into a sharp point, as the insect moves away. 

 These rostra are covered with the lather, in the same way 

 as the rest of the ootheca. Each female makes about five 

 of these egg-cases during four or five weeks; a single 

 union Avith the male appears to suffice for the fertilization 

 of the whole series of eggs laid in the season. The act of 

 forming the egg-case occupies about an hour. The in- 

 cubation period occupies from forty-four to forty-eight days. 

 The young nymphs in one ootheca hatch out almost 

 simultaneously. The embryos are developed in the egg 

 with their heads pointing towards the free surface of the 

 ootheca, on the side opposite to its attachment to the 

 branch. In some way the embryo softens the end of the 

 cell in which it lies, and this falls outwards as a small disc 

 hanging by a silken thread, and setting the nymph free. 

 At the moment of hatching the nymphs come pouring out 

 of their cells, and hang each by a silken thread suspended 

 in the air ; this silken thread is not attached to the cerci, 

 which have not, I think, the function of spinnerets as 

 figured for another species by Brongniart. The thread 

 appears to be a single one of twisted strands, and to be 

 attached at one end to the silk lining of the egg-case, and 

 at the other to a very delicate silk membrane which enfolds 

 the body of the nymph. The nymphs, clad in this 

 membrane, have a distinctly maggot-like appearance. 



