OF THE DEVELOPMENT OF THE FOETUS, ( 37 



rudiment in its descent meet the semen in its ascent, and that the transfer of the semen 

 beyond the womb may be the cause of extra uterine pregnancy. 



IV. Of Superfatati'm. M. de Bouillon (Kullet. de la FaaiL et dfi la Soci&e de 

 cine, JVb. 3.) has adduced an instance of superfoetation in a Negress. At the end of her 

 pregnancy she was delivered of two male children, full-grown, and of the same propor- 

 tions, but the one a Negro and the other a Mulatto. The mother, after a long resistance, 

 confessed that she had connexion the same evening with a white and a negro. Similar 

 instances have lately been detailed in the American journals, of which we shall only in- 

 stance the following : A white woman, near Philadelphia, is said by Dr. Dewees, to 

 to have been delivered of twins, one of whom was perfectly white, the other black. 

 The latter of these had all the characteristics of the African, whilst the former was de- 

 licate, fair-skinned, light-haired, and blue-eyed. Similar cases have been detailed by 

 Dr. Elliotson, and Drs. Norton and Stearns," of New-York. 



Superfcetation, in our opinion, can only take place under circumstances similar to 

 those which produced it in the foregoing instances : in them, it would seem, that there 

 had been connexion with different individuals within a short space of time. We con- 

 ceive that, when the decidua is thrown out and the ovium has formed its connexions, 

 superfostation is then impossible, unless in the case of a double uterus. 



Of the Development of the Textures and Organs of the Foetus. 

 Note KK* -^ 



It was our intention to have illustrated this subject at considerable length ; but we 

 have so far exceeded our limits that we must no^ be brief. 



At first the embryo appears to be only a semi-liquid vesicle, and to consist of minute 

 globules disseminated through a more fluid medium, which presents an oval or spheroid 

 form.* As the embryo advances, the proportion of solid matter increases, and continues 

 to increase to the termination o.f the life of the individual. The h'rsjt stage of its exist- 

 ence resembles that oi' the polypus ; and the globules which may be observed in its 

 otherwise homogeneous texture, closely resembles those which are observed in the 

 nervous system. At first the embryo is colourless ; it afterwards presents a gradual de- 

 velopment of colour, and at last, a coloured fluid may be discerned. From a state of or- 

 ganization, consisting merely of -disseminated globules, fibres, membranes, and vessels, 

 come Successively into existence. The organs, as we have already said, are not formed 

 at once : they are gradually developed. Even particular systems do not assume at once 

 their form of organization, but are developed by degrees, and run through the same 

 stages of organization as may b$ remarked in the animal scale. This is particularly re- 

 markable, ss respects the development of the nervaussystem.f (&ee the note on this 

 subject. ) 



The exterior form of the fetus seems to be assumed before its tissues attain any conside- 

 rable degree of consistence. The glandular viscera are at first formed in isolated parts. The 

 globules of the nervous system first appear ; these become united into cords and gan- 

 glia, t The vessels commence in isolated vesicles, which become elongate^ and connected 



* Mr. Bauer says that he has detected the human ovum on the eighth day from co- 

 ition. It consisted of two membranes ; the external one open throughout its length, 

 but with its edges turned inwards, like the shells of the g-enus voFuta , the internal 

 membrane pointed at one end and obtuse at the other, slightly contracted in the mid- 

 dle, and containing a slimy fluid and two vesicles. 



f It would appear that in the process of the growth of the embryo, even of man ? 

 that, during the first days of its existence,, the nervous system can only be traced as it 

 exists in the polypi ; its globules seem dispersed through the embryal structure : as 

 the ovum advances the ganglial branches, and the ganglia themselves make their ap- 

 pearance. 



-t Viewing the nervous system throughout the numerous classes of animals, and 

 tracing the process of its formation from the embryo up to the period of perfect fatal 



