20 



THE MATURATION OF THE EGG OF THE MOUSE. 



24 hours p.p., respectively), which were in the oviduct along with other 

 eggs in Stages VII and VIII. The eight eggs of Stage VII which were 

 from the oviduct came from six mice killed at from 15 to 17 hours p.p., 

 all being associated with eggs in Stage VIII. Of the three eggs of Stage 

 VII which were still in the ovary, one was from a mouse killed 22f 

 hours p.p., and two were from two mice killed 15^ and 16 hours p.p., 

 respectively. Of the eggs in Stage VIII, many were in the oviduct even 

 as early as 14! hours p.p. Among a few (7) mice, however, having all 

 their eggs in Stage VIII, in three (killed 14^, 19J, and 22^ hours p.p., 

 respectively) eggs occurred in the ovary, in the periovarial space, and in 

 the oviduct; in two (killed 14! and 28 hours p.p., respectively) eggs were 

 found in both ovary and oviduct; in one (killed 14I hours p.p.) eggs were 

 discovered in both ovary and periovarial space; and in another (killed 

 16 hours p.p.) the periovarial space and oviduct contained eggs. In 

 Stage III some eggs were observed in the ovary 28^ hours p.p. It fol- 

 lows, therefore, that ovulation occurs from 14^ to 28^ hours p.p., and 

 that eggs when discharged may be in any stage from the end of the 

 "equatorial-plate" stage of the first spindle (Stage IV b) to that of the 

 second spindle (Stage VIII). 



Table 4. — Mice killed during ovulation, showing location of eggs and 

 hours p.p. when they were obtained. 



*Eggs in Stage VII in only one oviduct. Eggs in Stage I were also 

 found, but in the ovary of the opposite side of the body. 



As already mentioned (p. 12), out of 85 mice artificially inseminated 

 31 produced fertilized eggs. No attempt is made here to analyze ex- 



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