142 G. CARL HUBER 



of the abnormal ova of the class described, and especially is this 

 true for older stages, present normal relations to the uterine 

 mucosa and the walls of the decidual crypt after implantation, 

 and so far as may be determined by structure, give evidence of 

 normal absorption of maternal hemoglobin in stages in which 

 such absorption is pertinent. It may be argued that a single 

 ovum may be less favorably placed in relation to embryotroph 

 or pabulum, and as a result of unfavorable nutrition, develop 

 abnormally. This is difficult to conceive for stages in which the 

 ova lie free in the lumen of the uterus, namely, to about the be- 

 ginning of the seventh day after the beginning of insemination, 

 when embryotroph or pabulum must be relatively evenly dis- 

 tributed. The presumption, it would seem to me, in such cases 

 is in favor of regarding the primary cause of the abnormal de- 

 velopment as inherent in the ovum. 



Separation of the first two blastomeres and the presence of two 

 egg-cylinders in a single decidual crypt are regarded as chance 

 findings and as of rare occurrence, since each was met with only 

 once in the material at hand. 



LITERATURE CITED 



Literature on pathologic ova of the albino rat is lacking. For the literature 

 of all but the more recent work, dealing with comparative experimental tera- 

 tology, the bibliographies accompanying the chapters of O. and R. Hertwig 

 may be consulted; for that dealing with the pathology of human ova, the bib- 

 liographies accompanying the contributions of F. P. Mall may be consulted. 



HERTWIG, O. 1906 Missbildung und Mehrfachbildung, die durch Storung cles 

 ersten Entwicklungsprozesse hervorgerufen werden. Hertwig's Hand- 

 buch der vergleichenden und experimentellen Entwickelungslehre der 

 Wirbeltiere, Bd. 1, Part 1; Fischer, Jena. 



HERTWIG, R. 1906 Der Furchungsprozess. Hertwig's Handbuch, Bd. 1, Part 1. 



MALL, F. P. 1900 Welch Festschrift, Johns Hopkins Hospital Reports, vol. 9. 

 1903 Vaughan Festschrift, Contributions to medical science, G. 

 Wahr, Ann Arbor. 



1908 A study of the causes underlying the origin of human monsters. 

 Jour. Morph., vol. 19. 



1910 The pathology of the human ovum. Keibel and Mall, "Manual 

 of Human Embryology." Lippincott Company, Philadelphia. 



