250 MR. MORLEY KOBKRTS OX THE FUNCTION OF 



is there for imagining such machinery coiihl result in a complex 

 sei'ies of adaptations such as the uterus and what we may call its 

 habits and customs in dealing with the embryo from the entrance 

 of the ovum till birth ? Even- those who adapt to their o^^•n 

 ideas some theory of large discontinuous variation will, in the 

 end, be compelled to attribute the uterine giowth and functions 

 to a mystic power or virtue in the original germ. They may 

 follow some philosophers and " unpack "' powers out of a con- 

 jurer's bag without telling us how they got there. Yet if we 

 regard the uterus as the result of tissue reactions under abnormal 

 stimuli, being guided in research by the processes seen every day 

 in disease, the variations, whether small or large, continuous or 

 discontinuous, assume an aspect neither fanciful nor mystical, 

 and our need for biological faith is reduced to a decent scientific 

 minimum. 



The fact that the embryo acts upon the maternal organism as 

 a parasite against which the mother has to be protected, is 

 commonly recognized, but I have not seen the obvious conclusion 

 drawn that the whole history of the mammal must have been 

 due originally to a pathological accident in some one or more of 

 their ancestors. The mammalian animal still lays eggs, but they 

 are not extruded. When such retention first took place, it must 

 have been due to an accidental pathological delay of the travelling 

 ovum, owing perhaps to catarrh of the tube. Even now the 

 mother has to be rendered immune to the products of the offspring. 

 Many of the phenomena of early gestation are those of immuni- 

 zation, in many cases a very slow process, as is shown in human 

 beings by vomiting and malaise. It has, moreover, not been 

 clearly or generally recognized except by pathologists that the 

 very methods by which the ovum attaches itself to the uterine 

 wall a,re, so far as the hostess is concerned, actually pathological 

 and bordering on the malignant. Yet they have resulted in a 

 series of protective reactions which save the parent and permit 

 the growth of the parasite. Tlie method by which the ovum 

 becomes partially buried in the tissues is obviously of a destruc- 

 tive kind and curiously analogous to the malignant processes 

 seen in chorion-epithelioma. Bland-Sutton remarks, " This disease 

 is instructive because the erosive action of the trophoblast is the 

 physiological type of the invasiveness so characteristic of many 

 varieties of cancer." It may, I think, be added that it is the 

 balance established by reaction which makes the trophoblastic 

 action physiological. 



That the influence of the ovum on the undeveloped tube must 

 have been of an exceedinglj'^ dangerous character is now seen in 

 tubal pregnancies during which the chorionic villi frequently 

 penetrate the wall of the tube, which does not react as powerfully 

 as the uterus. Such a process in the uterus, which is itself a tubal 

 dilatation, is now normal because these villi, the earlier nutrition 

 roots or organs of the parasite, are prevented from injuring the 



