1897.] or THK LEGS IN THE BLATTID.T. 913 



of sufficient space for running about, was the chief cause of this 

 degree of mortality. That it was abnormally high seems probable, 

 especially in A-iew of the facts which will be mentioned later on, 

 concerning the hatching of the egg-cases. Moreover, though 

 Cockroaches once established in a building may become extremely 

 numerous, their slowness in spreading in the neighbourhood is 

 well known, and it is probable that we by no means understand 

 what conditions are most favourable to this imported species. I 

 succeeded, however, in maintaining a few individuals in health for 

 nearly two years and one lived for rather over that time, and 

 eventually escaped from confinement. Bread and cake were always 

 readily eaten, but the animals seemed to pay no attention to a 

 moist sponge always kept in the cages. With large numbers in 

 one cage it was impossible to observe how often any one individual 

 made a meal, but Dr. Sharp ' has called attention to the very small 

 amount of food that is required to maintain a Cockroach in good 

 condition, and that many weeks of starvation seem to make little 

 difference to the animal. In the case of my own Cockroaches, a 

 weak individual was never attacked by his companions, but the soft 

 parts of the dead were soon devoured, as were all cast skins not 

 removed from the cages. These latter were certainly not always 

 eaten bv their owners, though occasionally they were. 



Occurrence of the Ecclyses. — On this subject the monograph of 

 Miall and Denny ^ contains the following statement in quotation 

 of Cornelius ' : — " The first change of skin occurs immediately after 

 escape from the egg-capsule, the second four weeks later, the 

 third at the end of the first year, and each succeeding moult after 

 a year's interval. At the sixth month the insect becomes a ' pupa,' 

 and at the seventh (being now four years old) it assumes the form of 

 the perfect insect. The changes of skin are annual and, like ferti- 

 lization and oviposition, take place in the summer months only. 

 These statements are partly based on observations of captive 

 Cockroaches, and are the only ones accessible ; but they require 

 confirmation by independent observers, especially as they altogether 

 differ from Hummel's account of the life-history of Blatta germanica, 

 and are at variance with the popular belief that new generations 

 of the Cockroach are produced with great rapidity." 



The observation of Hummel ^ referred to is that Phylloclromia 

 germanica performs six ecdyses between April and September, 

 and becomes adult within seven months from hatching out of 

 the egg-capsule. My own observations on the post-embryonic 

 development of S. orientalis may now be described. 



In the first place great difficulty was experienced in obtaining 



1 Cambr. Nat. Hist. v. p. 229. 



^ ' The Structure and Life-history of the Cockroach {Pcriplcmeta orientalis) ' 

 (London, 1886), p. 23. 



^ ' Beitrage zur naheren Kenntniss von Periplaneta orientalis.' Elberfeld, 

 1853. 



' " Quelques observations sur la Blatte germanique." Essais Entomolo- 

 giques. I. St. Petersbourg, 1821. 



