CAUSE OF HYPERTROPHY OF SURVIVING OVARY 77 



two hours at 40°C., a fixed amount of the solution was applied 

 to the intestine of the albino rat. During the time when the 

 tracing was taken the container of the solution in which the 

 intestine was immersed was amply oxygenated at a temperature 

 of 38°C. In all cases the same amount of extract was used so 

 as to make the results comparable. 



The kymographic records show^ that the extracts from both 

 normal and surviving ovaries produce a sUght increase in the 

 tonus of the rat intestine. We failed, however, to find any 

 conspicuous difference between the extracts obtained from the 

 normal and from the hypertrophied ovaries. Although this 

 similarity may be due to too great dilution of the extracts, yet 

 the nearly identical character of the two kinds of curves would 

 indicate that, so far as the extracts are concerned, the surviving 

 ovary does not differ appreciably from the normal ovary. 



Nevertheless, it will be desirable to make the test with much 

 more concentrated extracts before any definite conclusion is 

 reached. 



SUMMARY 



1. So far as my observation goes, semispaying has no influence 

 upon the growth of the body of rats. 



2. The compensatory hypertrophy of the surviving ovary 

 occurs independent of coitus or pregnancy and has already 

 appeared at three to five weeks after operation (in this case 

 forty-one days of age). Before puberty the weight of the sur- 

 viving ovary is about 40 per cent heavier than the normal ovary, 

 but after puberty it is 100 per cent or more above that of the 

 control rats. 



3. The number of ova in the right ovary, excised at twenty 

 days, and in the left surviving ovary in the same rat are about 

 the same, despite the fact that the weight of the surviving 

 ovary is two to ten times greater than that of the right ovary 

 at the time of removal. On the other hand, the number of ova 

 in the surviving ovary is 12 per cent less than that in the ovary 

 of the corresponding side of the controls in the same litter, and 

 at the same ages; nevertheless, the surviving ovary weighs one 



