18 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



XVI, Fig. 5, m ; which thus forms a follicle around a central core of cells, 

 n. These central cells are the ovarian eggs. In young stolons, and at the 

 root or proximal end of old ones, these eggs are small and crowded 

 together, Plate XXXI, Fig. 4, but as we pass outward towards the tip of 

 the stolon, Figs. 5, 6, 7, 8 and 9, they gradually grow larger, and the 

 number cut by each ^transverse section grows less and less, until (Plate 

 XXXIV, Fig. 4, m, and Plate XV, Fig. 2, m), they are pulled out into a 

 series of single eggs. 



The figures in Plates XXI and XXXI are from young stolons which 

 are carried by embryos like those which are shown in Plate XLI, Figs. 3 

 and 5 ; but even in mature stolons, which have set free many generations 

 of buds, there is an undifferentiated portion of the germinal mass at the 

 root, as is shown in Plate XLI, Fig. 8, which is a little nearer the root of 

 the stolon than the figures on Plate XXXIV. 



On Plate XLI, Fig. 7, is a longitudinal section through the middle of 

 the germinal mass of a very young embryo, before it has become differ- 

 entiated into a central core of eggs and a peripheral follicle of epithelium. 

 Figure 8 is a transverse section through the germinal mass of a fully 

 grown stolon at its root, where the undifferentiated or embryonic germ 

 cells are multiplying by karyokinesis, while Fig. 9 is from the same 

 stolon a short distance from the root, where there is a continuous follicle, 

 filled with ova, which latter have entirely lost the power of vegetative 

 multiplication. 



In both young stolons and old ones the undifferentiated germ cells 

 multiply by indirect division, and one or two cells with nuclear figures 

 may be found in each section, but as we pass towards the tip of the 

 stolon and the central cells assume the characteristics of ova, Plate 

 XXXI, Fig. 5, from a young stolon, and Plate XLI, Fig. 9, from a mature 

 stolon, the egg cells cease to multiply, although they increase in size, both 

 yolk and nucleus growing rapidly. The material for this growth is 

 furnished by follicle cells, Plate XXXI, Figs. 5 and 6, which migrate 

 from the peripheral layer, inwards among the egg cells, where they 

 degenerate and break down. 



In a stolon which is mature and ready to produce buds, the repro- 

 ductive organ consists of a single row of fully developed ova, Plate XV, 

 Fig. 2, n, surrounded by a follicular sheath which consists of an egg 

 capsule of flattened cells, and an epithelium of thicker cells on the ventral 

 or ha3mal side of the eggs. See also Plate XXXIV, Figs. 2 and 4. The 

 flattened cells give rise to the follicular capsule of the egg, Plate X, Fig. 



