242 First Maturation Spiiullc of Allolohopliora Fatida 



centriole at the upper pole, the centriole of the lower pole was not on the same 

 plane. Photo. 91 shows two unstained chromosomes on a different plane from 

 the two in Photo. 90. Fixative, platino-osmic. Stain, Photo. 90 iron hasma- 

 toxylin followed by dilute Bismarck brown. Photo. 91, unstained. 



Photos. 92a and b. x 1000. Two consecutive sections of a first matur- 

 ation spindle of a fertilized oocyte in a freshly deposited cocoon. We have 

 twelve photographs of this spindle showing all the eleven chromosomes and 

 both centrioles. In the two selected for reproduction both centrioles are 

 shown and a few of the chromosomes. 92a was focused for the centriole, 

 sacrificing a sharp definition of the chromosome, and 92b was focused for the 

 peripheral centriole, only one of the four chromosomes being on the same 

 plane. Fixative, chromo-acetic. Stain, iron haematoxylin. 



Photos. 93 to 97. X 710. Sections of nucleoli of oocytes from ovary. Fix- 

 ative, Rabl's picro-sublimate. Stain, iron haimatoxylin. 



Photos. 98a and b. x 710 and 1000. Section of a nucleolus of an oocyte 

 from the ovary. Fixative, Platino-osmic. 98a unstained. 98b stained with 

 iron hsematoxylin. 



PLATE VI. 



The sections in Photos. 99 and 105 are o/j, those of 102 and 106 are 5 ,«, all 

 the others are 2^/^ //. 



Photo. 99. x 710. Unstained section of an unfertilized oocyte from a 

 freshly deposited cocoon showing the first maturation spindle at the meta- 

 phase, with two of the eleven chromosomes. The peripheral centriole is not 

 visible in this unstained section, but the centriole at the lower pole of the 

 spindle could be clearly seen. Fixative, platino-osmic. 



Photo. 100. x 1000. Section of an unfertilized oocyte from an immature 

 cocoon still encircling the clitellum of the worm. This photograph shows the 

 peripheral pole of the first maturation spindle with the centriole and thread- 

 like rays typical of chromo-acetic preparations. The two membranes of the 

 egg with the substance between are clearly defined, and this is shown also 

 in Photo. 99. Fixative, chromo-acetic. Stain, iron hsematoxylin followed by 

 dilute Bismarck brown. 



Photo. 101. x 1000. Section showing the centriole at lower pole of a first 

 maturation spindle of an oocyte from the receptaculum ovorum. Fixative, 

 Boveri's picro-acetic. Stain, iron haematoxylin followed by dilute Bismarck 

 brown. 



Photo. 102. x 710. Section showing the centriole at peripheral pole of 

 a first maturation spindle of an oocyte from the receptaculum ovorum. Fix- 

 ative, chromo-acetic. Stain, iron haematoxylin. 



Photo. 103. X 1000. Section showing the centriole at the lower pole of a 

 second maturation spindle of a fertilized oocyte from a cocoon. Fixative, 

 chromo-acetic. Stain, iron hsematoxylin. 



Photo. 104. X 1000. Section of the second maturation spindle of a 

 fertilized oocyte from a cocoon, showing the centriole at the lower pole, but 

 not in the centre of the sphere. Fixative, chromo-acetic. Stain, iron haema- 

 toxylin. 



Photo. 105. X about 1000. Section showing the centriole at the lower pole 

 of a second maturation spindle of a fertilized oocyte from a cocoon. Fixative, 

 saturate corrosive sublimate. Stain, iron haematoxylin. 



