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Show 914 MR. H. H. BRINDLEY ON THE REGENERATION [Nov. 30, undoubtedly newly batched individuals. Between 500 and 600 egg-capsules were collected from bakehouses aud kitchens in Cambridge, very many of them immediately after deposition by the females. At first they were placed in an incubator in the Zoological Laboratory in a constant temperature of 38° C , but so little success attended this method that tbe capsules obtained later were left undisturbed, as nearly as possible in the exact spots where they had been deposited. But from the whole number of capsules observed, only 20 hatchings were obtained, the total number of young thus raised being 210, an average of 10*5 young from each capsule, which in this species normally contains 16 embryos. If this observation may be regarded as resting on a fairly sufficient number of instances, it would seem that a large proportion of the egg-cases deposited do not hatch out, and also that some of tbe young in those that do hatch never appear. As ail the cases that hatched did so within a few days after deposition, while the others examined long after were invariably found to be quite brittle and dried up iuside, it seems unlikely that the non-hatching of the greater number observed was merely a result of allowing insufficient time for batching to take place. If this view be accepted, it affords a partial explanation of the well-known tardiness with which this species spreads. With regard to the time of year when ecdysis occurred, the following observations were made. The mutilated Cockroaches commenced living in captivity during the first three months of the year. The dates of 235 observed ecdyses were distributed thus:- March 4 ecdyses. April 12 May 18 June 92 „ July 72 August 33 „ September .... 4 „ That the number of ecdyses during the maximum period increased rather more rapidly than it declined, is apparent from the following :- May, 3rd • „ 4th June, 1st „ 2nd „ 3rd „ 4th July, 1st „ 2nd „ 3rd „ 4th .... 4 .... 8 ... 12 42 .... 21 .... 17 ... 23 .... 22 .... 10 .... 17 ecdyses. 55 55 55 55 55 » 55 55 55 |