966 OF GENERATION. 



if it be not, it gradually disappears ; so that, from this difference in the subse- 

 quent changes (which may be probably attributed to the increased determination 

 of blood to the whole Generative apparatus when it is in a state of excessive 

 functional activity), the corpus luteum which is characteristic of the pregnant 

 state is usually a much larger and more highly organized body, than that which 

 is commonly found in the ovary of the unimpregnated female. But it is also 

 unquestionable that an unusual development of the fibro-cellular substance 

 may sometimes take place without impregnation ; whilst, on the other hand, the 

 changes which usually follow impregnation may take place so much less charac- 

 teristically than usual, that the corpus luteum, even at an early period of preg- 

 nancy, may be no larger than that which is often found where pregnancy has 

 not occurred. These variations, which seem mainly to depend upon differences 

 in the degree of vascular excitement of the ovaries, accompanying and succeeding 

 the extrusion of ova, render it impossible to draw any definite line of demarca- 

 tion, by which we may at once determine what are, and what are not, the results 

 of conception ; but the following practical rules, deduced from a consideration of 

 all the circumstances yet known, may be laid down for the guidance of those 

 who find it desirable to have some standard of judgment : "1. A Corpus Lu- 

 teum, in its earliest stage (that is, a large vesicle filled with coagulated blood, 

 having a ruptured orifice, and a thin layer of yellow matter in its walls), affords 

 no proof of impregnation having taken place. 2. From the presence of a 

 Corpus Luteum, the opening of which is closed, and the cavity reduced or ob- 

 literated, only a stellate cicatrix remaining, also no conclusion as to pregnancy 

 having existed or fecundation having occurred can be drawn, if the corpus luteum 

 be of small size, not containing as much yellow substance as would form a mass 

 the size of a small pea. 3. A similar Corpus Luteum of larger size than a 

 common pea would be strong presumptive evidence, not only of impregnation 

 having taken place, but of pregnancy having existed during several weeks at 

 least ; and the evidence would approximate more and more to complete proof, 

 in proportion as the size of the corpus luteum was greater." 1 



1 See Dr. Baly's " Supplement to Miiller'8 Physiology," p. 57; where a comprehensive 

 account will be found of all the recent researches bearing upon this question. [The 

 reader is also referred to the elaborate prize essay of Dr. J. C. Dalton, in the " Transac- 

 tions of the American Medical Association" for 1851, in which the difference between the 

 corpora lutea of menstruation and pregnancy is clearly made out. The following are 

 some of the characteristic marks by which the two may be recognized : 



" I. The corpus luteum of pregnancy arrives more slowly at its maximum of development, 

 and afterward remains for a long time as a very noticeable tumor, instead of undergoing 

 a process of rapid atrophy. 



II. It retains a globular or only slightly flattened form, and gives to the touch a sense 

 of considerable resistance and solidity. 



III. Internally, it has an appearance of advanced organization, which is wanting in the 

 corpus luteum of menstruation. 



IV. Its convoluted wall, particularly, attains a greater development, this portion mea- 

 suring sometimes so much as three-sixteenths to one-fourth of an inch in thickness, while 

 in the corpus luteum of menstruation it never exceeds one-eighth, and is almost always 

 less than that. This difference in the thickness of the convoluted wall is one of the most 

 important points of distinction. It will be much more striking when viewed relatively to 

 the size of the central coagulum. 



V. The color is not, by any means, so decided a yellow, but a more dusky and indefinite 

 hue. 



VI. If the period of pregnancy is at all advanced, it is not found, like the corpus luteum 

 of menstruation, in company with unruptured vesicles in active process of development. 



The histories and observations detailed by Dr. Dalton will serve to show how very im- 

 perfect are some of the marks which various writers have heretofore laid down as dis- 

 tinguishing 'true' from 'false' corpora lutea. Dr. Montgomery* gives seven charac- 

 teristics by which, he says, the 'false,' or 'virgin' corpora lutea may be recognized. 



* " Signs uud Symptoms of Pregnancy," p. 245. 



