The finding of microspheric individuals of Orbitoides apiculatus Schlumberger var. gruenbachensis Papp containing numerous megalospheric embryos demonstrates one of three types of reproduction in orbitoidal foraminifera. The multinucleate microspheric form produces haploid megalospheric individuals by a schizogonic type of reproduction. The peripherally situated embryos must have been able to destroy the walls of bypassed chambers, as they moved from the center of the test towards the periphery. In some cases, the direction of the advance of the embryos can be observed. The apparent dissolution was probably accomplished by the activity of enzymes. Schizogony in Orbitoides apiculatus var. gruenbachensis A study of specimens of Orbitoides apiculatus Schlumberger var. gruenbachensis Papp, found in the vicinity of Bilecik in Anatolia about 80 miles southeast of Istanbul, has shown two microspheric individuals possessing 31 and 8 megalospheric embryos respectively on their test margins. In a previously described microspheric specimen of Orbitoides medius d'Archiac, 23 megalospheric embryos were found along the test periphery (Merig, 1966). Another specimen found contained 5 megalospheric embryos on the test edge (Cassan and Sigal, 1961). According to the results now obtained, three types of reproduction may be seen in orbitoidal foraminifera. The multinucleate microspheric individual produces megalospheric forms by a schizogonic type of reproduction. These megalospheric forms, which are haploid, produce microspheric individuals by sexual reproduction, i.e., gamogony. The third type is the asexual production of megalospheric forms by the division of the megalospheric forms themselves. The present writer's observations have shown that the multinucleate microspheric schizont produces haploid megalospheric individuals. One of my specimens, found near Uyukoy, has a diameter of 1 2.3 mm. The embryo diameter is 30 microns. The central equatorial chambers have a width of 60-90 microns and a height of 30-45 microns, while those at the periphery range from 21 2 to 454 microns in width and from 242 to 272 microns in height. The equatorial chambers thus become increasingly larger towards the periphery (plate 1, figure 1). Furthermore, growth rings are evident, as in the other specimens of Orbitoides apiculatus Schlumberger var. gruenbachensis Papp. Those rings nearest the periphery are composed of the largest equatorial chambers. As may be observed (plate 1, figure 1), megalospheric embryos are not evenly distributed all around the test, but occur only in a certain part of the test. Not all of the megalospheric embryos are aligned in a single plane, as previously mentioned by the present writer (Meri(, 1966). This can also be seen clearly in the present photographs. Some of the embryos were cut exactly through the center, but the section was cut tangentially in others, and these embryos have a smaller apparent size. Although some bodies, thought to be embryos, were noticed in different parts of the test, they were neglected because of the absence of a definite form. On the other hand, the hollow of a former embryo can be clearly seen in plate 1, figure 5. This embryo has either left the parent individual or was destroyed when the section was made. Counting all of these, one can state that the megalospheric embryos which are present in this individual, too, are more than 31 in number. Although some embryos are found singly, micropaleontology, vol. 16, no. 2, pp. 227-232, pis. 1-2, april, 1970 227 This content downloaded from 157.55.39.176 on Sat, 09 Apr 2016 06:10:58 UTC All use subject to http://about.jstor.org/terms