. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. THE VITAL PHENOMENA OF THE CELL 201. Fig. 95. — Cnnstructioii of the spindle out of two half- spindles, the fibrils of Tvbich are attached to the daughter- segments. (From van Bene- den and Neyt, PI. VI., Fig.«.) to its construction and origin. Whilst the first observers considered that the spindle consisted of most delicate fibrils, which stretched continuously from pole to pole, van Beneden (YI. 46) and Boveri (VI. 6) are of opinion that these fibrils are broken at the equator, and
. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. THE VITAL PHENOMENA OF THE CELL 201. Fig. 95. — Cnnstructioii of the spindle out of two half- spindles, the fibrils of Tvbich are attached to the daughter- segments. (From van Bene- den and Neyt, PI. VI., Fig.«.) to its construction and origin. Whilst the first observers considered that the spindle consisted of most delicate fibrils, which stretched continuously from pole to pole, van Beneden (YI. 46) and Boveri (VI. 6) are of opinion that these fibrils are broken at the equator, and that, in consequence, the spindle is composed of two separate and distinct half-spindles (Fig. 95). They contend that the half-spindles are attached directly with the ends of their fibrils to the nu- clear segments, and in consequence are of mechanical use in nuclear division, in that they shorten or contract like muscle fibres after the segments have divided into daughter-segments, and thus draw the daughter-segments, which are at- tached to them, in opposite directions. On the other hand, Flemming {VI. 14) for the tissue cells of Salamandra, and Strasbnrger (VI. 72) for plants, still adhere to their old theory, that spindle fibrils, stretching nninterruptedly from pole to pole, do exist. The observations made by Hermann, which have been already mentioned, are especially convincing concerning the undivided condition of the spindle; they call to mind my description and representation of the formation of the spindle in the germinal vesicle of Asteracanthion (VI. 30a, PI. VIII., Figs. 3, 4). In both cases a very small, undivided spindle may be observed between the poles, which, are situated near to one another (Fig. 96), at that period when the nuclear segments are a good way off, and so cannot hide it at all ; ib is seen to grow gradually, as its fibrils in- crease in length, until it reaches its full size. The explanation of this discrepancy, as has been suggested by Herman
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