No. 2.] THE OVARIAN EGG OF LIMULUS. igi 



of stains often bring it prominently into view even after all 

 hopes of observing it have been abandoned. 



Occasionally it may be more excentric. It is often very 

 large, and consists of densely packed granules, which grade 

 gradually into the surrounding protoplasm in which more con- 

 spicuous traces of the reticulated arrangement of the granules 

 can be seen (Fig. 114). Here a zone of similar granules 

 extends around the periphery of the egg, under the perivitelline 

 layer of protoplasm. It is made conspicuous by means of the 

 Biondi-Ehrlich stain, in which it takes a darker tinge than the 

 rest of the cytoplasm. By means of Lyon's blue it also appears 

 as a much darker body. By means of the double stain of 

 erythrosin and cyanin it can be differentiated as a blue body, 

 the rest of the cytoplasm being red (Fig. 104). The staining, 

 however, must be applied with the greatest of care, and in a 

 manner that can be learned only by repeated experiment. 

 Having once acquired the necessary skill, however, it is a 

 comparatively easy matter. From this it is not to be inferred 

 that it is all a matter of staining, for the preliminary method 

 of preserving is of even greater importance. Even with the 

 best method of staining, it is to be observed only in the most 

 perfectly preserved material. This is true not only of the later 

 stages just described, but it is true also of the earlier stages. 



In this description no attempt has been made to exhaust the 

 subject, but merely to give the more prominent features of the 

 body as it appears in the various phases of the growing egg. 



All the figures in the plates, beginning with Fig. 48, PI. XIV, 

 are drawn with a Leitz camera, obj. 5, oc. i-Leitz. Figs. 

 42-49 are drawn with a Leitz ^^ oil immersion. 



Fig. 32 is one of the smallest eggs observed in the adult 

 ovary, drawn with a camera, Leitz ^'^ oil immersion. 



Interpretation and Summary. 



After the last division of the oogonia to form a follicle, the 

 centrosome, with its surrounding structures, persists in the 

 cytoplasm. It has been observed in this case, not only during 

 karyokinesis, but after the last reconstruction of the nucleus. 



