THE SEXUAL ORGANS. 



259 



691). The mode in which this change is 

 brought about was, as regards the histological 

 conditions, until a recent period, it may be 

 said, entirely unknown; but, in the main 

 points, is now sufficiently made out. The 

 principal changes occur in the muscular coat, 

 to which the increased volume of the uterus is 

 chiefly to be assigned, and there are two pro- 

 cesses which participate in common in its pro- 

 duction : in the first place, an enlargement of 

 the pre-existing muscular elements; and secondly, 

 a new formation of them. The former is so 

 considerable, that the contractile fibre-cells, 

 instead of a length of 0'002— 0003'", and 

 width of 0-002'", as elsewhere, in the fifth 

 month present a length of 006 — 0*12 /// , and 

 width of 0-0025— 0-006'", or even 001'", and 

 in the second half of the sixth month, a length 

 of 01— 0-25'", a width of 0004— 0006'", 

 and a thickness of 0*002— 0-0028'"; conse- 

 quently, their length is increased from seven 

 to eleven times, and their width from twice to 

 five times. The new formation of muscles may 

 be observed in the first half of pregnancy, espe- 

 cially in the innermost layers of the muscular 

 coat, where newly originating cells, O'Ol — 

 00 18"' in size, in all stages of transition into 

 fibre-cells of 002 — 003'", always occur in 

 great quantity ; but it takes place also in the 

 outer layers. After the sixth month, this 

 origination of muscles seems to cease ; at least 

 in the twenty-sixth week, in the whole uterus 

 I have found nothing but the above-mentioned 

 colossal fibre- cells, and no longer any trace of 

 their earlier forms. Like the muscles, the 

 fibrous tissue which unites them also increases, 



Fig. 268. a, muscular fibre-cell from a gravid uterus, at the 

 sixth month; b, its middle portion, after treatment with acetic 

 acid, exhibiting the appearance of a membrane ; c, nucleus of 

 the fibre-cell ; x 350 diam. 



Fig. 268. 



