88 CHILD. [VOL. 1. 



are sufficient to show that the presence of a sphere and centro- 

 some in the cytoplasm may often be due to some other cause 

 than an approaching or just finished mitosis. In this prelimi- 

 nary paper it is desired to describe a case which the writer 

 believes may be included under this head. 



Some months since, in the preparation of mammalian ovaries 

 for histological work, the ovary of a pregnant dog was sec- 

 tioned, and, being double-stained with Delafield's haematoxylin 

 and erythrosin, showed the stroma to consist almost entirely of 

 comparatively large, polyhedral cells with a coarse cytoplasmic 

 network and a round nucleus containing clumps of chromatin 

 of varying size and position. But the most striking feature of 

 the preparation was the fact that each cell apparently possessed 

 a large sphere J deeply stained with erythrosin. In fact the whole 

 appearance of the slide reminded one of an amphibian testis. The 

 older corpora lutea showed cells somewhat similar in structure 

 but more vacuolated, and without any trace of the sphere. 



Examination of the ovaries of pregnant rabbits revealed the 

 fact that the structure of the stroma cells was almost perfectly 

 identical with that found in the pregnant dog. In this case, 

 however, it was found that these cells appeared only in tlie 

 ovary of tJie pregnant female. Rabbits which were not preg- 

 nant showed the usual structure of the ovarian stroma without 

 any trace of the sphere in any of the cells. One exception 

 must be made to this statement, viz., the case of a rabbit exam- 

 ined during the period of lactation a few days after the young 

 were born. The ovary of this female showed the same structure 

 as was found in the ovaries of pregnant animals. 



My observations along this line extend at present no farther 

 than this: I have examined three pregnant rabbits and one in 

 lactation, and in all cases have found the structure referred to 

 in the stroma cells. I have also sectioned the ovaries of three 

 non-pregnant rabbits, and in no case was even a trace of a sim- 

 ilar structure to be found. I have had no opportunity to extend 

 my observations on the dog beyond the one case mentioned, 

 that of a pregnant female where the sphere was first seen. 



1 Mr. W. H. Packard, a fellow of the University, who was preparing the sec- 

 tions, was the first to observe this structure. 



