GROWTH OF EGGS AND EGG-STRINGS IN NEPilKLlS. 201 



The rachal side bears what I have ah-eady called the ger- 

 mogen {gcr., figs. 2 and 4), and is thus easily recognised. 



We may now conclude our description of the second 

 stratum. In addition to the pigmented system of fibres 

 before described and the loosely packed cells, there occurs on 

 the rachal side'a system of longitudinal muscle-fibres. The 

 few fibres (1 — 3 in number) representing this system run 

 nearly parallel along the inner limit of the second stratum, 

 thus forming a sort of muscular axis to the rachal thicken- 

 ing (long., figs. 3 and 4). Like all the muscle-fibres of the 

 ovary- wall, they are broadest at the points occupied by the 

 nuclei. They are of considerable length, and taper toward 

 either extremity. Whether they end in a point, or ulti- 

 mately anastomose with their fellows, as in the case of the 

 circular muscle-fibres, I am not prepared to speak with 

 certainty. 



The third system of muscles, constituting the third 

 stratum, presents some interesting peculiarities. The trans- 

 verse fibres are disposed in two longitudinal series, each of 

 which encircles one half of the ovarial tube, beginning in 

 one — say the rachal line — and terminating in the other 

 (mediad line). The nuclei of each series of semicircular 

 fibres (fig. 3, s. cir.) fall nearly in one line, situated about 

 midway between the two extremities. The line of nuclei 

 lies somewhat nearer to the mediad (b) than the rachal line 

 (a), which is explained by the fact that the mediad end of 

 each fibre is more strongly curved than the opposite end. 

 These fibres taper from the broad middle portions (ca. '015 

 mm.) which bear the nuclei towards both ends. The course 

 and arrangement of these will perhaps be best understood if 

 we confine our attention for a moment to a single strand. 

 According to what has been said, the position of the rachal 

 and the mediad line in the anterior portion of each ovary is 

 such that a horizontal plane joining these two lines would 

 divide the tube into an upper and a lower half. If novsr we 

 take a fibre in the upper half and, starting from the highest 

 point, which coincides nearly with the nucleus, follow it 

 towards the mediad end, we find not only that it descends as 

 it describes the arc of its quadrant, but also that it gradually 

 bends forward until, in the neighbourhood of the mediad 

 line, it has a longitudinal direction. A curve of double 

 curvature is thus formed. The mediad portion usually 

 bifurcates one or more times, and the branches either anas- 

 tomose with branches belonging to the opposite series, or, 

 iifter crossing them, terminate in points. On the other side 

 of the nucleus a similar curve is formed, the only difference 



