400 THE PHYSIOLOGY OF REPRODUCTION 



evidence in its favour, the greater munl>er of leucocytes in the blood 

 of the umbilical vein than in that of the artery. This view, which 

 explained satisfactorily the passage of non-diffusible materials, 

 subsequently received wide support. Thus Wiener l said : " It may 

 be held as nearly without doubt that leucocytes cross from the 

 maternal to the foetal blood," and Preyer 2 considered the passage of 

 leucocytes " indisputable." The first objection was raised in a paper 

 by Paterson. 8 In it he recorded three cases of pregnancy complicated 

 by leucocythtemia in the mother, and stated that the infants appeared 

 quite normal and healthy, and their blood was of the usual colour 

 and not white like the mothers'. These results were corroborated 

 in similar cases by Cameron 4 and Sitnger, 5 who actually counted the 

 foetal leucocytes and found no increase. More recently, Spire and 

 Pen-in/ 1 in a case where the mother had pernicious anaemia, found 

 that the foetal blood was practically normal. These observations, 

 and the inability of other investigators to demonstrate healthy 

 leucocytes in the tissues intervening between the maternal and foetal 

 blood, have led to the abandonment of Rauber's theory. 



But though maternal leucocytes do not pass as such straight 

 into the foetal blood, they may be important in another way. In 

 Ruminants, Bonnet 7 has drawn attention to the enormous number 

 of degenerated leucocytes in the uterine milk, and demonstrated 

 their absorption by the ectoderm, and similar observations have been 

 recorded in Carnivores. In these orders leucocytes undoubtedly 

 form a part of the embryonic nutriment. In the rest of the 

 deciduate Mammals they seem to play a less important part. 



III. THE DECIDUA 



In the uterine mucosa during pregnancy the most noticeable 

 change occurs in the interglandular tissue of discoid placentae, in 

 which decidual cells are formed. Various opinions have been held 

 regarding their origin. Langhans, Hennig, 8 and others held that 

 they were enlarged and modified leucocytes, but the}- could not 



1 Wiener, "Die Ernahrung des Fotus," Samml. Klin. Vortrnge, No. 290. 

 Preyer, Spend fe Physiologic cfe* Embryo, 1883. 



3 Paterson, "Cases of Acute Leucocythsemia in connection with Pregnancy," 

 Edinburgh M><l. ./..///., 1870. 



4 Cameron, " The Influence of Leucaemia upon Pregnancy," Internal. Jour, of 

 the Ned. ,SV., 1888. 



5 Sanger, " Ueber Leukiimie bei Schwangeren und angeborene Leukamie," 

 Arch. /. '/,////>/., vol. xxxiii., 1888. 



" Spire and Pen-in, " Un Cas d'Anemie pernicieuse de la Grossesse," Bull. d<> 

 li S<: .rnhtt.-t. <t ,/.- <;, m . de Paris, (Nov.) 1912. 



Bonnet, " Tlier Embryotrophe," Dwits. med. Woch., 1899. 



8 Hennig, >Y-////.-/' at*-,- den Kav der mci<*<-l<H>-l,en Placenta, etc., Leipzig, 

 1872. 



