834 RICHARD ASSHETON. 



parts of each of the three segments. The same characters of 

 clear and darker portions are recognisable as in the two- 

 segment stage. 



Eig. 4 is a drawing from a fresh specimen taken from the 

 Fallopian tube of another sow. This and one other, which 

 was also in the four-segment stage, are the only two embryos 

 I have ever obtained from the Fallopian tube of the pig. 

 The same features were present as regards inner and outer 

 portions of each segment. 



The four segments were not of equal magnitude. 



The following measurements were made while the specimen 

 was quite fresh : 



Diameter of the whole specimen from outer 



edges of zoua radiata . . . '164 mm. 



Thickness of zona radiata .... •016 „ 



Diameters of the largest sphere . . '064 „ X "066 mm. 



Diameters of the smallest sphere . . '060 „ X "060 „ 



These two segments formed one pair in contact with each 

 other. At right angles to this pair was the pair formed by the 

 other two segments, which were of equal size and did not 

 quite touch each other. 



Diameters of each '060 mm, x '064 mm. 



The diameters of one polar body were . '015 „ x *010 „ 



The second polar body was too indistinct to be measured. 



I was not able to detect any difference in the colour or in 

 the composition of the several segments, either while fresh or 

 after the application of osmic acid and stains. There would 

 seem to be distinct diflFerence in size. 



The following measurements from another specimen made 

 after fixation give similar results. 



Pair in contact : 

 Diameters of the larger segment . . '056 mm. x "058 mm. 

 Diameters of the smaller segment . . •056 „ x '054 „ 



Pair widely separated and at right angles to the preceding : 



Diameters of larger segment . . . •OSO mm. x 'Oei mm. 

 Diameters of smaller segment . . . '047 „ x "058 „ 



