238 First Maturation Spindle of Allolobophora Foetida 



Photo. 26. X about 1100. Section of upper pole of a first maturation 

 spindle with sphere and centriole in fertilized oocyte from freshly deposited 

 cocoon. There is a centriole at the lower pole of this spindle, but we selected 

 this photograph as more interesting for reproduction, because it is much more 

 difficult to demonstrate a centriole at the upper pole, when it is close to the 

 periphery. Fixative, Flemming's fluid without acetic acid. Stain, iron haem- 

 atoxylin, followed by dilute Bismarck brown. 



Photos. 27 and 28. X 1000. Two sections of the same germinal vesicle of 

 an oocyte first order from a receptaculum ovorum. There are four intervening 

 sections between the two reproduced here and the principal nucleolus of 

 Photo. 27 shows no connection with the chromatic filaments. Fixative, 

 platino-osmic. Stain, iron hsematoxylin followed by dilute Bismarck brown. 



Photo. 29. x 1000. Section of a germinal vesicle of an oocyte first order 

 from a receptaculum ovorum, showing the large vacuolated nucleolus and 

 the smaller accessory nucleolus. Fixative, Picro-sublimate. . Stain, iron 

 haematoxylin, followed by dilute Bismarck brown. 



Photo. 30. X 1000. Section of a germinal vesicle of an oocyte first order 

 from a receptaculum ovorum showing chromatic filaments in transverse 

 section and two short granular filaments crossing each other. The large 

 vacuolated nucleolus is in the 3rd, 4th and 5th sections from that of Photo. 30. 

 Fixative, corrosive-acetic (5 per cent acetic). Stain, iron haematoxylin fol- 

 lowed by dilute Bismarck brown. 



Photo. 31. x 1000. Section of a germinal vesicle of an oocyte first order 

 from a receptaculum ovorum showing the large vacuolated nucleolus and an 

 early stage of the segregation of the chromatin into chromatic filaments. 

 Fixative, corrosive sublimate. Stain, iron haematoxylin. 



Photo. 32. x 1000. Section of lower pole of second maturation spindle 

 showing four of the eleven chromosomes approaching the lower pole. This 

 section was photographed to show a precocious formation of one of the 

 eleven vesicles not due normally until the telophase. The centriole is in the 

 next section. Fixative, chromo-acetic. Stain, iron haematoxylin. 



Photo. 33. X 1000. Section of first maturation spindle, showing five of 

 the eleven chromosomes. This egg is one of eight found in an immature 

 cocoon encircling the cliteilum of a worm. The four chromosomes which are 

 on the same plane are clearly defined and show a decided difference in size. 

 We have six photographs of this spindle showing all the eleven choromosomes 

 but cannot spare space for more than one reproduction. Fixative, corrosive 

 acetic (10 per cent acetic.) Stain, iron haematoxylin, followed by dilute 

 Bismarck brown. 



Photo. 34. x 1000. Section of a germinal vesicle of an oocyte first order 

 from a receptaculum ovorum, showing the typically injurious effect of 

 chromo-acetic on the nucleoplasm. This photograph shows a distinct net knot 

 resembling a large nucleolus with two vacuoles, but it is unmistakably an 

 artefact, for the principal nucleolus of this egg is present in the seventh sec- 

 tion from the one i*eproduced in this photograph. Stain, iron haematoxylin 

 followed by dilute Bismarck brown. 



Photo. 35. x 710. Section of a vacuolated nucleolus of an oocyte from the 

 ovary. Fixative, corrosive sublimate followed by osmic acid. Unstained. 



