Abstract
Certain aspects of the general problem of the immunity of the albino rat to Cysticercus fasciolaris, begun in 1929, 1 have been investigated. In one set of experiments rats were given series of immunizing injections of: (a) a 1% suspension of powdered worm material (Taenia taeniaeformis, the adult stage of C. fasciolaris) in physiological saline solution; (b) an 0.84% suspension of powdered worms which had been subjected to prolonged extraction with ether in a Soxhlet or Pickel extraction apparatus; (c) a 1% suspension of finely ground worms which had been quickly frozen while alive with carbon dioxide snow and stored in evacuated glass ampoules for 3 months at —10°C.; (d) a 1% suspension of powdered worm material of Taenia pisiformis, a closely related species from the intestine of the dog. All rats, with litter mate controls, were fed with equal portions of a uniform suspension of onchospheres. At autopsy 35 days later normal sized cysts (4-5 mm. diameter) were present in the livers of control animals; while development of the larvae had been completely, or almost completely inhibited in the rats of groups a, b, and c. In these the larvae were represented for the most part by minute spots. In the livers of those animals injected with powdered T. pisiformis material (group d) the cysts developed as well as in the control rats, so that it has been demonstrated that no nonspecific immunity developed from the injection of this closely-related worm material.
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