. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. ITS CHEMICO-PHYStCAL AND MORPHOLOGICAL PROPERTIES 58 I have observed (IT. 19) that the germinal spot is composed of two substances in Helix, Tellina, and Asteracanthion, as well as in Anodon. Asteracanthion (Fig. 31) is of special interest, as the separation into two substances {p n, n u) only becomes distinctly- visible when the germinal vesicle commences to break up and to form the polar spindle out of its contents. Finally, in the description of the structure of the resting nucleu
. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. ITS CHEMICO-PHYStCAL AND MORPHOLOGICAL PROPERTIES 58 I have observed (IT. 19) that the germinal spot is composed of two substances in Helix, Tellina, and Asteracanthion, as well as in Anodon. Asteracanthion (Fig. 31) is of special interest, as the separation into two substances {p n, n u) only becomes distinctly- visible when the germinal vesicle commences to break up and to form the polar spindle out of its contents. Finally, in the description of the structure of the resting nucleus, attention mast be drawn to one other important point. According to the age or stage of development of a cell, the resting nucleus may present very considerable variations in nil its separate parts: as to the appearance of its framework, andastothe numher,size, and peculiarities of its nucleoli. Thus, as Flemming (II. 10) remarks, " In young eggs from the ovaries of Lamellibranchs, this twofold composition of the large nucleolus is not to be seen ; it only develops in the mature egg.'' Above all, the germinal vesicles of the eggs undergo during their de- velopment important metamor- phoses, which at present have been but little investigated, whilst their significance is still less understood. The same is true of the nuclei of sperm mother cells. I have en- deavoured to follow accurately these changes of form in such cells obtained from the testis of Ascaris megalocephala (II. 19 b), which are very suitable for the purpose. As is shown in Fig. 32, form A gradually becomes transformed into form J>, and this during the process of development of the spermatozoon into form G ; the youngest sperm mother cells (B) have naked nuclei containing dense nuclear frameworks, and superficially-placed nucleoli; this form develops in older cells (C) into a vesicular nucleus with a distinctly marked membrane. In the vesicle a few linin threads are extended through the nuclear sap, the
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