Modifications Induced in the sexual Cycles of the Protozoa of Cryptocercus by Chabge of Host*

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Abstract
SYNOPSIS.: The following types of transfauntions were made: from nymphs is an early stage of their molting period to nymphs 1‐50 days before ecdysis and vice versa; from recently molted nymphs to nymphs in all stages of the molting period and vicve versa. In such transfaunated half or more of the protozoa in a donor host were transferred to a recipient host. The recipient hosts wee defaunated with oxygen by subjecting them to 60 psi for 2 hours, twice the minimum time necessary to kill all their protozoa. Transfaunations were made 24 hours after defaunation.The sexual cycles, as a result of these transfaunation experiments, in addition to being prevented altogether in several genera, were modified principally in two ways: they were shortened to less than half the time required under natural conditions; they were lengthened, in some genera, from two days to over two months. Whether shorteing or lengthening occurs depends on the type of host used in the experiment. And the factor in the host that is responsible for the modifications is the ecdysone titer; transfaunation from a lower to higher to a lower titer, in general, serves to lengthen it.