THE MORPHOLOGY AND BEHAVIOR OF THE INTRACELLULAR BACTEROIDS OF ROACHES

¹ From the Department of Zoölogy, Indiana University

1. The staining reactions, morphology and occurrence both intra- and intercellularly definitely preclude the intracellular bacteroids of the roaches from the category of mitochondria and link them closely to both the diphtheroids and the Rickettsia.

2. The number of bacteroids between the oöcyte membrane and the follicle cells increases until there is a uniform layer two or three bacteroids thick. By differential increase of the oöcyte surface this layer becomes thinner along the sides.

3. Before the egg is oviposited, the original oöcyte membrane breaks down and permits the bacteroids to enter the cytoplasm.

4. As the embryo develops, the bacteroids, accompanied by nuclei similar to the vitellophag nuclei, move in masses to the center of the yolk.

5. Later a few bacteroids from this central mass move posteriorly between yolk granules through the incomplete margins of the gut epithelium into the body cavity. From there most of them are taken up by the cells of the lateral lobes of the fat bodies while a few are caught between the cells of the forming ovaries.

6. The bacteroids within the ovariole seem to lie dormant for several weeks, then they multiply rapidly and spread over the surfaces of the enlarging oöcytes.

7. Newly enlarged oöcytes from the germarium are infected by bacteroids moving anteriorly from older oöcytes.

8. Bacteroid behavior varies between roach species with differences in number of bacteroids, in structure of the ovary, and in position of development of the embryonic rudiment.

9. All bacteroid migrations appear to be passive.

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