THE AMERICAN LOBSTER. 151 



no longer spheroidal, have become shrunken and scattered about the meshes of a 

 protoplasmic network. There are, besides, globules (fig. 15;3, y. s.), probably of an 

 albuminous nature, which resemble spherules of yolk, and lie either in the lumen 

 of the fold or are embedded in the protoplasmic reticulum. They are most abundant 

 in the reticulum, where they sometimes occur as large granular masses. In tig. 

 145, plate 40, a single large spherule (y. s.) of this kind is seen interpolated between 

 the follicular cells. A number of nuclei surround it and, however anomalous its 

 position, the appearance is not artificial. In other cases, where no degenerative 

 processes are at work, the lumina of these folds are filled with a fine granular residue. 

 The intimate relations which these structures bear on the one hand to the vascular 

 sinuses, and on the other to the growing ova, point to their probable function, that of 

 the formation of yolk. If this is the case, it is evident that the ovarian glands can 

 play but a minor role in this process. The massive yolk of the ripe egg is formed for 

 the most part in the protoplasmic reticulum of the egg cell from materials which are 

 drawn directly from the blood. A third source of the yolk is the follicular cells 

 themselves, large masses of which pass into the egg at this stage, where they undergo 

 complete degeneration, as I have pointed out in another paper (93, 94), and shall 

 describe more fully presently. 



THE OVARY AFTER OVULATION. 



The appearance of the ovary shortly after egg-laying is represented in plate 38, 

 fig. 136. It has collapsed from its distended condition, and is now of a yellowish- white 

 color, flecked with green and orange spots. The green bodies are ripe ova which failed 

 to be forced out at the time of the last laying. The ducts are often full of them (com- 

 pare fig. 119). The orange specks are the remains of similar eggs left over from the 

 previous ovulation. While the latter have thus been in the ovary for at least two 

 years, they are not yet completely absorbed. The primary membrane of the egg still 

 remains, inclosing a small disorganized residue (fig. 150). 



The structure of an ovary at this period is shown in fig. 139, plate 39. The external 

 eggs were in an early stage of yolk segmentation, showing that not more than thirty- 

 six hours had elapsed since the last egg-laying. The ovarian lobe is now a solid mass 

 of tissue, the youngest ova being disposed about the axis, the older at the periphery. 

 Irregular blood sinuses penetrate to every part, between folds of follicular epithelium. 

 These folds take the form of irregular pouches and represent, as Bumpus has shown 

 (30), invaginations of the ovarian epithelium. This is better seen in Palinurus, or in 

 the ovary of the adolescent lobster. 



The ovarian glands have now attained their greatest prominence, and their relation 

 to the growiug eggs is well illustrated in fig. 139, plate 39, and figs. 151, 152, plate 41. 

 In fig. 151, from a horizontal section, the eggs lie in strings, or rather tiers, between 

 the double walls of the epithelial folds, which dip down vertically from the surface of 

 the ovary. This is from a later stage than fig. 152, which represents a section through 

 the central or terminal boundary of the fold. It is from the same ovary as fig. 139, 

 where the glands are in the ascendant. The glandular cells have the form of tall 

 columns, the nuclei lying at their deeper ends. Cell boundaries are very vague, the 

 central ends of the cells merging into what appears as a granular reticulum. The 

 columnar cells, though apparently stopping short at the sides of the egg, are directly 

 continuous with the less conspicuous cells of the true follicle. This glandular co?cum 

 resembles, in sectiou, a narrow bag with an egg pushed into its mouth. A thin layer 



