6l6 FOOT AND STROBELL. 



EXPLANATION OF PLATE XXXVL 



Photo. 12. Section (3/^) of oocyte second order, showing the head of the 

 spermatozoon, its middle-piece within the aster and a part of the tail. (The miss- 

 ing part of the head is in the next section.) Fixative, corrosive-sublimate. 

 Stain, iron-haematoxylin. x 660. 



Photo. 13. Vignetted section (3 /u) of oocyte second order, showing part of 

 the head of the spermatozoon, the middle-piece, and (probably) a tiny piece of the 

 proximal end of the tail. Stage of development about the same as that of photo. 

 12. Fixative, 2% osmic in 70° alcohol. Stain, iron-haematoxylin. x 950. 



Photo. 14. Vignetted section (3 jx) of oocyte second order. Stage of devel- 

 opment about the same as that of photo. 13. Fixative, corrosive-sublimate. 

 Stain, iron-haematoxylin. x 950. 



Photo. 15. Vignetted section {3 /x) of oocyte second order. Stage of devel- 

 opment about the same as that of photo. 14. The section has cut transversely 

 two middle-pieces which are within the aster. (The heads of the two sperma- 

 tozoa are in adjacent sections.) Fixative, corrosive-sublimate. Stain, iron- 

 haematoxylin. x 950. 



Photo. 16. Vignetted section (3 /x) of oocyte second order, showing the head 

 of the spermatozoon separated from the middle-piece and contracted into a rela- 

 tively thick short rod. Within the aster the middle-piece and probably a piece of 

 the tail. Fixative, corrosive-sublimate. Stain, iron-haematoxylin. X 950. 



Photo. 17. Section (3m) of oocyte second order, showing the contracted 

 head of the spermatozoon separated from the middle-piece, which is within the 

 sphere, but over-printing has obliterated it. The hyalin globules larger than those 

 seen in the normal living egg at this stage. Fixative, Hermann's fluid without 

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



Photo. 18. Vignetted section (3 /u) of oocyte second order. Stage of devel- 

 opment about the same as that of photos. 16 and 17. Middle-piece not in the 

 center of the sphere. Fixative, corrosive-sublimate. Stain, iron-haematoxylin. 

 X 950. 



Photo. 19. Vignetted section (3 /u) of oocyte second order. Middle-piece 

 nearly in the center of the sphere. The contracted head of the sperm is in the 

 adjacent section. Fixative, Flemming's fluid (strong). Stain, iron-haematoxylin. 

 X 950. 



Photo. 20. Vignetted section (3 ix) of oocyte second order, showing a trans- 

 verse cut through the middle-piece of the spermatozoon, its position in the sphere 

 eccentric. The head of the spermatozoon is in the next section. Fixative, 

 corrosive-sublimate. Stain, iron-haematoxylin. X 950. 



Photo. 21. Vignetted section (3//) of oocyte second order, showing a little 

 later stage of development than that of 16-19. The middle-piece is beginning to 

 disintegrate. The contracted head of the sperm is seen in the next sectioa. 

 Fixative, Perenyi's fluid. Stain, iron-haematoxylin. X 950. 



Photo. 22. Vignetted section (3 fx) of oocyte second order at about the same 

 stage of development as that of photo. 21, the middle-piece showing like evidences 

 of disintegration. Fixative, picro-formalin. Stain, iron-haematoxylin. x 950. 



