Donald L. Price

Electron microscope study of Sarcocystis sp.

Abstract Sarcocystis sp. obtained from wild populations of grackles, Quiscalus quiscula (Linn.), were examined to clarify the effect of the parasite on the host. Electron micrographs are presented to show areas of muscle destruction adjacent to the parasite which appear to be mechanically produced by the parasite. The microtubules within the villus-like projections of the cyst suggest that their possible function is absorptive and/or conductive with regard to the production of a toxin or the conveyance of nutritive material to the developing cells. The proposed function of submembranous filaments and their relation to the conoid is discussed. Similarities in the ultrastructure to Toxoplasma and other protozoa tend to negate the relegation of Sarcocystis to the fungi and further emphasize its protozoan nature.

Dirofilaria magnilarvatum n. sp. (Nematoda: Filarioidea) from Macaca irus Cuvier. I. Description of the adult filarial worms.

A microfilaria was described by Poynton and Hodgkin (1939) from a macaque (Macaca irus) which was collected in the lower reaches of the Perak river in the state of Perak, Malay. Edeson (1954)* observed microfilariae in the peripheral blood of several M. irus collected in the state of Pahang, Malaya, which closely approximated the description given by Poynton and Hodgkin. Adult filarial worms collected later by Dr. Edeson and the author from one of these macaques were determined to belong to the genus Dirofilaria. After returning to the United States, the author had an opportunity to examine at Walter Reed Army Medical Center, Washington, D. C., National Institutes of Health, Bethesda, Maryland, and Eli Lilly Research Laboratories, Indianapolis, Indiana, a total of 510 M. irus believed to have originated in Malaya.** In 12 of these monkeys microfilariae were found similar to those previously observed in Malaya. Adult worms were collected also from several of these macaques, and the microfilariae were associated with them in most cases.

EPIZOOTIOLOGIC STUDIES ON FILARIOIDS OF THE RACCOON

Filarioid worms (Dirofilaria immitis, D. tenuis, Dipetalonema procyonis, and D. Ilewellyni) were discovered in raccoons (Procyon lotor) in Maryland. Raccoons were trapped in lowland, upland, and agricultural-residential areas, which were further classified as stream borders, poorly drained, and well drained. Data on incidence of D. Ilewellyni were analyzed on basis of host distribution within these areas to indicate type of habitat in which one might seek the vector. It was concluded that exposure takes place in the spring of the year. The arthropod found associated most often with the raccoon in spring was Ixodes texanus. Larvae of this tick which were fed on infected raccoons presented no evi- dence of development of the microfilariae. Feeding experiments were also conducted with mosquitoes: Aedes aegypti, A. canadensis, A. sollicitans, A. triseriatus, A. vexans, Culex pipiens, Anopheles punctipen- nis, and A. quadrimaculatus. Although microfilariae remained alive and active in the gut contents of all these mosquitoes for 2 days, only in Aedes aegypti did they enter the hemocele, but no developmental changes were noted and all microfilariae were dead by the eighth day. Although the intermediate host of D. llewellyni was not determined, evaluation of the accumulated data provides criteria for seeking the vector. It appeared unlikely that exposure of the raccoons took place in the den or that the filarioids were transmitted by an ectoparasite commonly found in raccoon dens. The data suggest that the vector is available only early in spring, although there are infected raccoons throughout the year. Prevalence in juveniles was 21 percent; in subadults, 64 percent; in adults, 87 percent.

New biological warm stage.

Summary A biological warm stage has been constructed which controls and measures the temperature of a special electrically-coated and transparent glass plate by means of a two-thermistor-beaded probe and auxiliary apparatus. The stage can also be used to control the temperature of media while under the microscope. Because of its sensitivity and versatility, the warm stage has unlimited possibilities for application in the field of biology.