. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. [124] OVUM. in most but not in all of which segmentation is complete. This process was first made known through the interesting researches of Kolliker*, in Miiller's Archiv., 1843, p. 68, and Bagge, in his Inaugural The memoir of Reichert in Miiller's Archiv., 1847, contains very correct views as to the formation of the spermatic cells. The accompanying figure from MeissnerJ, gives a representation of a remarkable form of the external capsule of the ova occurring in some of the Gordiacei (Mermis nigrescens
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. [124] OVUM. in most but not in all of which segmentation is complete. This process was first made known through the interesting researches of Kolliker*, in Miiller's Archiv., 1843, p. 68, and Bagge, in his Inaugural The memoir of Reichert in Miiller's Archiv., 1847, contains very correct views as to the formation of the spermatic cells. The accompanying figure from MeissnerJ, gives a representation of a remarkable form of the external capsule of the ova occurring in some of the Gordiacei (Mermis nigrescens}. Fig. 90*.. Mature ova of Mermis nigrescens. (From Meissner.') This figure is introduced to show the very pe- culiar capsule in which the ovum is enclosed. a. Ovum taken from the uterus with embryo enclosed; the chorion and shell capsule with cha- lazse or brush-like processes attached to the latter. b, c. The sholl capsule <•. burst across the equa- torial groove, allows the ovum b to escape with the chorion and embryo contained within it. The ova of Trematoda are generally of a long-oval form, and of middle size. They are enveloped by a shell membrane of consider- able firmness, and winch is not unfrequently of a dark brown colour. The yolk-sub- stance contains fat corpuscles simple and compound ; and there is a germinal vesicle present, which, however, from the deep colouration and other circumstances, is often very difficult of detection. In these animals an interesting peculiarity in the arrangement of the reproductive organs exists, in the separation of the germ-forming and yolk-forming portions from each other ; in the first of these organs germinal vesicles or clear nucleated cells alone being produced, in the other the opaque granular fatty matter which furnishes the vitellus. This arrange- ment was first described by Von Siebold in 1836.$ The germ organ is generally in the form of a rounded sac, which is filled with the nucleated germ-cells or vesicles in vari
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