REACTIONS OF CELL-BODIES AND PSEUDOPODIAL FRAGMENTS OF DIFFLUGIA

¹ UNIVERSITY OF VIRGINIA

1. In Difflugia separated pseudopodial fragments are recovered by their cell-bodies, as evidenced by over one hundred experiments. The species included in these observations were: D. acuminata, D. corona, D. pyriformis, D. spiralis, and D. vulgaris. The distances by which the fragments and their cell-bodies were separated ranged from a few micra to 1,500 micra. The unfavorable conditions under which reunion does not occur are: (a) Injury to cell with consequent failure on its part to extrude pseudopods; (b) separation from fragment by too great a distance; (c) evaporation of water before completion of reactions.

2. The severed fragments are not recovered as food, but enter again immediately into the protoplasmic structure of the cell-body. Such fragments are not reappropriated after they show visible signs of death.

3. In our observations fusion never occurred at the ends of pseudopods, but always took place along an extended mid-region. This indicates a physio-chemical difference between the ends and the middle of such pseudopods.

4. In some cases the severed fragments, which were only ectoplasmic in composition, were observed to take an active part in restitution. Not only did they move toward, but apparently shifted, their line of approach to correspond with the changing positions of their cell-bodies.

5. Fusion has not been observed to take place between two enucleated fragments, even though they be placed in contact.

6. Fusion between an individual of one species and a fragment from an individual of a different species has not been observed. The phenomenon seems to be specific.

7. Observations have been made in which individuals of the same species, obtained from the same wild culture, showed a decidedly negative response toward each other's fragments. Yet in other instances such cross-fusions did occur. This latter suggests the possibility of close genetic origin.