548 FOOT AND STROBELL. [Vol. XVII. 



EXPLANATION OF PLATE XLIII. 



The photos of this plate show different stages of the egg found in freshly de- 

 posited cocoons. The archoplasm in all cases is composed of masses of granules ; 

 but it is impossible to reproduce this structure satisfactorily without sacrificing a 

 proper reproduction of the rest of the cytoplasm. Photo 84 has been printed with 

 the aim of showing the structure of the archoplasm in the polar rings, and this 

 photo must be referred to as illustrating the finer structure of the archoplasm in 

 both the ovarian and the cocoon eggs. 



Except Photo 62, all the photos in this plate were taken at a magnification of 

 660 diameters. 



Photo 51, section (3 m) through the cytoplasm of an unfertilized oocyte, first 

 order. The first maturation spindle is at the stage shown in the egg of Photo 52. 

 The preparation is unstained, but the fixative has tinted the archoplasm yellow. 

 This print has been made very dark in order to show the two substances in the 

 cytoplasm, the dark granular archoplasm and a faintly differentiated, relatively 

 homogeneous substance which is much more difficult to stain. This is the sub- 

 stance which in some cases forms the network or rays, but we do not feel justified 

 in asserting how much of this condition is due to fixation. The dark printing of 

 the archoplasm has obliterated most of the osmophile granules which were black 

 in the preparation {cf. Photo 60 for osmophile granules at this stage of develop- 

 ment of the egg). Fixative, Hermann's fluid without acetic acid. 



Photo 52, section {lii) of an unfertilized oocyte, first order. To avoid oblit- 

 erating the centrosome the archoplasm here was not printed so dark as in Photo 51. 

 Only two of the eleven chromosomes are clearly shown in this section. The 

 chromosomes, archoplasm, and centrosome were tinted yellow by the fixative. Only 

 a few of the larger osmophile granules are shown {cf. Photo 60 for these). Fix- 

 ative, Hermann's fluid without acetic acid. Preparation unstained. 



Photo 53, section {3 ;u) through the cytoplasm (near periphery) of an unfer- 

 tilized oocyte, same stage of the egg as shown in Photos 51 and 52. The prepa- 

 ration was stained in iron-haematoxylin and the granular archoplasm sharply 

 differentiated. Fixative, 1% osmic acid in 70° alcohol. 



Photo 54, section (3 /u) of a fertilized oocyte, first order. The apex of the fer- 

 tilization cone is seen near the center of the section. The spindle is probably not 

 normal, for in all other preparations it has reached the anaphase when the fer- 

 tilization cone is present. The preparation suggests that the cytoplasm has reached 

 the stage of development necessary to the appearance of the fertilization cone, but 

 the spindle is retarded; it is not radial and has not reached the periphery. The 

 curved chromosome seen on the right is an exception. This preparation shows 

 aggregations of granular archoplasm through the cytoplasm. See Photos 51 and 

 53 (C^ Photo 61 for osmophile granules in eggs at this stage of development). 

 Fixative, corrosive sublimate. 



Photo 55, section (3 /x) of a fertilized oocyte, second order. Part of the sperm 

 sphere is shown near the center of the section and just above it a cross-section 

 through the head of the sperm, which at this stage is a short thick rod. Archo- 



