No. 3.] EGG OF ALLOLOBOPHORA FCETIDA. 541 



EXPLANATION OF PLATE XLI. 



The photos of this plate illustrate successive stages of the growth and distri- 

 bution of the yolk-nucleus (archoplasm) in the ovarian cells, from its first 

 appearance in the smallest cells near the proximal end of the ovary to its distri- 

 bution in the large cells at the distal end of the ovary — i.e., oocytes, first order. 

 All the photos are taken at a magnification of 660 diameters (Zeiss 2 mm. immer. 

 lens). All the preparations except Fig. 20 are stained with iron-hasmatoxylin. 

 Where it is stated that the fixation was followed by osmic acid, this was done to 

 demonstrate the presence of osmophile granules, and after these were studied in 

 the unstained preparations and sometimes photographed, the preparations were 

 stained in iron-hasmatoxylin. In the plates we shall use the term " archoplasm " 

 to designate the substance known as yolk-nucleus. In several of the original 

 velox prints one or more details have been slightly strengthened with a lead-pencil, 

 in order to insure a more satisfactory reproduction. If any of our readers should 

 wish to compare the reproductions with the original velox prints, one or more 

 may be obtained on request. 



Photo I, section (2^^) of three tiny oocytes showing the archoplasm close 

 to the nuclear membrane. The nucleolus is shown in only one of the cells. 

 Fixative, corrosive sublimate. 



Photo 2, section (2^/x) of a small oocyte with archoplasmic masses dis- 

 tributed through the cytoplasm. Fixative, Rabl's picro-sublimate. 



Photos 3 and 4, sections (2^^) of young oocytes. The archoplasm of photo 3 

 is in closer proximity to the nuclear wall than that shown in Photo 4. Fixative, 

 corrosive sublimate. 



Photo 5, section (3 /it) of a small oocyte. Archoplasm massed near the nucleus. 

 Fixative, corrosive sublimate followed by osmic acid. 



Photo 6, section (2^/1) of two small oocytes. Archoplasm closely attached 

 to nuclear wall. Fixative, corrosive sublimate. 



Photo 7, section (5 ytt) of a larger oocyte. Archoplasmic masses throughout the 

 cytoplasm. Fixative, corrosive sublimate. 



Photo 8, section (2|/ti) of a young oocyte. Peripheral archoplasmic masses. 

 Fixative, picro-sublimate, followed by osmic acid. 



Photos 9 and 10, sections (2\p) of growing oocytes. Masses of archoplasm 

 scattered through the cytoplasm, nearly encircling the nucleus. Fixative, cor- 

 rosive sublimate. 



Photos II and 12, sections (2^^) of growing oocytes. Archoplasm massed 

 around the periphery of the cell. Fixative, picro-sublimate, followed by osmic 

 acid. 



Photo 13, section (2^/x) of a growing oocyte. Masses of archoplasm scattered 

 through the cytoplasm. Fixative, corrosive sublimate. 



Photo 14, section {2\tJ.) of a growing oocyte. Archoplasm massed at the 

 periphery of the cell and scattered through the cytoplasm. Fixative, picric acid. 



Photo 15, section (2|/u) of a growing oocyte. Archoplasm scattered through 

 the cytoplasm. Fixative, corrosive sublimate. 



Photo 16, section (2i/i) through the cytoplasm of a growing oocyte. Scat- 

 tered archoplasmic masses and many of the osmophile granules. These granules 



