1888.] MICROSCOPICAL JOURNAL. 148 



egg? The facts in the case are that the egg, as we see it in our section, con- 

 sists of protoplasm, a central vesicle with many resemblances to a cell nucleus, 

 and an outer membrane like a cell wall. These data alone would be enough 

 to lead us to pronounce the egg a cell, were it not for its extraordinary size, 

 and for the presence of so much ' foreign matter,' the yolk. 



The follicle wall. — Beyond the egg. following it closely, and without a 

 break at any point (except such breaks as are due to the imperfection of the 

 observer's manipulation), is a thin line. This line, in the section, is built 

 up, by interpreting many serial sections, into a wall which envelopes the en- 

 tire egg. In fact, the egg is entirely enclosed by a capsule called its follicle. 

 Sections which pass through the end of the egg often give fine oblique or 

 flat surface views of the follicle, and very readily and indisputably establish 

 its histological character. Such a section is shown in fig. 3. Examination 

 of the follicle wall (in very good sections only) at a point between the eggs, 

 as at d, fig. I , will show two rows of flat cells. If from this point the sec- 

 tion be traced along, the wall can be followed double for some distance, but 

 finally diverging into two parts which run oft' each one to enclose its particu- 

 lar egg. The wall is thus proved to enclose the egg completely, and to be 

 entirely distinct, histologically, from that of adjoining eggs. The follicle 

 furnishes beautiful pictures of the pavement epithelium. In the cross sec- 

 tions of the cells, at the middle of the eggs, the nucleus can be seen thicker 

 than the cell elsewhere, while between the cells the boundary cannot be seen 

 at all. In the sui'face views (fig. 3) the polygonal cells, with their outlines 

 faintly traced, show very well the character of the follicle. 



The itnmature egg. — In the corners left between the large eggs may be 

 seen small bodies, shown in fig. 5, which are the predecessors of large eggs, 

 the young of a later generation. These bodies have the same situation as the 

 large ones, being completely enveloped by a cellular capsule, their follicle 

 similar in character to the capsule of the mature egg. The immature egg 

 presents a number of points of unlikeness to the mature egg, and it is 

 hardly likely that the observer would connect the two as different only in 

 age, were it not for its relation to the egg follicle. The immature egg 

 is invested with a membrane with all the characters of an ordinary cell 

 wall. The size is not much greater in the case of some ovules than that of 

 the follicle cells. The ovule contains throughout, besides its germinal vesi- 

 cle, pure protoplasm like other cells, with no trace of the yolk so prominent 

 in mature eggs. The centre of the ovule is occupied by a relatively large 

 nucleus or vesicle in which much the same appearance is seen as in mature 

 ova, differences being, perhaps, more individual than due to characteristics 

 of different ages. So far as any difference seems general, it is in that the 

 nuclei are not so distinctly in a peripheral zone, but scattered through the 

 egg they should be shown iDy darker spots in figure 5. It must be stated here 

 to prevent the chance of mistake that the mature egg, as here described, is 

 the egg before union with spermatic fluid of the male has taken place. The 

 matin-e egg is the egg ready for that union ; we have nothing to do here with 

 the changes in the egg during fertilization and later, but only the description 

 of the ovarian egg. 



\To be continued.^ 



The Cosmopolitan Magazine has of late made very decided advance, and the May 

 number is, in our opinion, the best one thus far issued. It has taken a place among 

 the best magazines. The use of colors in the illustrations, at first hardly an addition, 

 is in the colored illustration of Moncure D. Conway's admirable article on ' The Ped- 

 igree of the Devil' a very decided success. We must congratulate the new manage- 

 ment upon this very great improvement. The tone of the entire magazine is elevated, 

 though the articles are popular and likely to interest a wide class of readers. 



