5 14 FOOT AND STROBELL. 



EXPLANATION OF PLATE XXXV. 



Photo, i. An entire egg (oocyte first order). This photograph was taken 

 by Dr. Charles G. Fuller, of Chicago, in the fall of 1893. He focussed on the 

 fertilization cone, and although the magnification is not great, the photograph 

 appears to us as very satisfactory in showing the size of the cone in relation to 

 the entire egg. Fixative, chromo-acetic. Stain, alum-cochineal. The reproduc- 

 tion of the cone in this figure has not been uniformly successful. 



Photo. 2. Section (3 \j) of oocyte first order. Fertilization cone cut longi- 

 tudinally. Head of the sperm within the cone, showing a spiraljtwist. Cytoplasm 

 typical of chromo-acetic preparations at this stage. The osmophile granules are 

 stained. Fixative, chromo-acetic. Stain, iron-haematoxylin. x 660. 



Photo. 3. Section (3 jj) of oocyte first order. Fertilization cone cut trans- 

 versely near its apex. Fixative, corrosive-sublimate. Stain, iron-haematoxylin. 

 X 660. 



A comparison of photos. 2 and 3 illustrates the relative shrinkage produced 

 by the two fixatives and the difference in the topography of the cytoplasm. 



Photo. 4. Vignetted section (3 ix) of oocyte first order. Fertilization cone 

 cut transversely about midway between its base and apex. Fixative, osmic and 

 acetic acid. Stain, iron-haematoxylin. X 660. 



Photo. 5. Section {3 p) of a pathological oocyte first order. Fertilization 

 cone cut longitudinally. Fixative, corrosive-sublimate. Stain, iron-haematoxylin. 

 X 660. 



Photo. 6. Vignetted section (3 ju.) of a polysperm oocyte first order. The 

 fertilization cone has almost disappeared, but shows that it contained two sper- 

 matozoa. Fixative, picro-formalin. Stain, iron-haematoxylin. x 660. 



Photo. 7. Vignetted section {3 /x) of oocyte second order, showing a sperm 

 aster, with the middle-piece of the sperm near its center. The head of the sperm 

 appears in the next section as a rod, as shown in photos. 8, 16, 17, 18. Fixative, 

 osmic and acetic. Stain, iron-haematoxylin. x 660. 



Photo. 8. Section (7 jj) of oocyte second order, showing a part of the sperm 

 head contracted into a rod and an indication of the sperm aster, the section being 

 through the periphery of the aster. This photo, was taken by Dr. Fuller, 1894. 

 Fixative, chromo-acetic. Stain, iron-haematoxylin. X about 400. 



Photo. 9. Section (7 \x) of oocyte second order, showing male aster, the 

 center of which is stained so deeply that the middle-piece is completely obliter- 

 ated. Photographed by Dr. Fuller, 1894. Fixative, chromo-acetic. Stain, iron- 

 haematoxylin. X about 400. 



Photo, id. Vignetted section (3 m) of oocyte second order, showing a part of 

 the head of the sperm surrounded by sperm granules. Fixative, corrosive-sub- 

 limate. Stain, iron-haematoxylin. x 950. 



Photo, ii. Section (3 /x) of oocyte second order, showing a part of a con- 

 tracted head of a spermatozoon which appears to have been fixed in the act of 

 constricting off a sperm granule. Fixative, Flemming's fluid (strong). Stain, 

 iron-haematoxylin. X 660. 



