392 JAS. P. HILL. 



unclosed^ but just closed in trunk region ; distinct sinus rhom- 

 boidalis enclosing primitive streak ; fore-limb buds ; median 

 heart anlage ; blood circulating ; distinct auditory grooves. 



Both uteri were examined microscopically, and were found 

 to have undergone exactly the same changes. It may here be 

 noted that such changes as have occurred are not limited to 

 any special region of the mucosa, but occur uniformly all 

 over it. 



Tiie general appearance of the uterine wall under a low 

 power is shown in fig. 3. Owing to the enlargement of the 

 uterus as a whole, the serosa and muscularis appear to be 

 somewhat thinner than in the preceding stage. The mucosa is 

 approximately of the same thickness as in that stage, but has 

 altered considerably in appearance. The uterine glands (fig. 

 3, gl.) are now for the most part widely separated from each 

 other, and the interglandular connective tissue appears greatly 

 attenuated. It consists of a very delicate retiform tissue, and 

 is permeated by abundance of lymph coagulum, while nume- 

 rous leucocytes are also distributed through it. 



The glands appear the same as in the preceding stage. The 

 mucosa is now much more vascular than in Stage A. The 

 syncytial lining of the uterus has undergone furtlier enlarge- 

 ment and differentiation. The layer has an average thickness 

 of "035 mm., i. e. it is somewhat thicker than in Stage A. 

 Further, its inner surface is now found divided up into a series 

 of numerous close-set lobular projections of somewhat irre- 

 gular size (fig. 4, syn. I.). The greater number of the syncy- 

 tial nuclei are disposed in relation to these lobules, in many 

 cases filling them completely, in other cases forming an irre- 

 gular layer in the marginal protoplasm of the lobule. Scat- 

 tered nuclei also occur in the superficial portion of the syncy- 

 tium, but not abundantly. Like the syncytial protoplasm, 

 the ovalish or rounded nuclei stain deeply. They now present 

 the appearance of typical resting nuclei, a fact which suggests 

 that the further enlargement of the syncytium is not to any 

 great extent at least accompanied by active division of the 

 nuclei. 



