Abstract
In view of the successful results of numerous experiments on passive transfer of immunity 1 against infection with onchospheres of Taenia taeniaeformis, it was not surprising to find that a degree of protection was transmitted to the offspring of female rats actively immunized against this worm or infected with the larval stage. More than 250 such young rats have been used in a series of experiments begun in 1930.
The young of immune and control (stock) rats were infected at weaning, or at varying intervals thereafter, by feeding, by means of a stomach tube, equal portions of a uniform suspension of infective onchospheres. In most such instances cysts (2 to 5 mm. diameter) were present in the liver of control animals at autopsy 4 to 5 weeks later, while cyst development was completely, or almost completely, inhibited in the offspring of infected or immunized females. The results of a typical experiment are shown in Table I.
In these experiments protection of the young of infected females was greater than that of the offspring of actively immunized females. In either case this immunity is passive and has not been found to persist beyond about 6 weeks after birth.
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