AS TO THE HEREDITY OF ACQUIRED COT^DITIONS. 489 



of the tongue, more marked anteriorly. There was no affection 

 of any of the special senses, nor any disturbance of deep or 

 superficial sensation, nor was there any difference of tempera- 

 ture between the two sides. 



. (3) Mendel* has reported the results of a very thorough 

 examination he made of the fifth nerve in a case of facial 

 hemiatrophy, of many years' standing, in a woman. This 

 woman had also atrophy in the region innervated by the left 

 musculo-spiral nerve. She died from phthisis. Her ease was 

 first described by Romberg and more recently by Virehow. The 

 symptoms were those of a typical left facial hemiatrophy. 

 Mendel found all the branches of the left fifth nerve, from their 

 origin to their termination, the seat of a proliferating neuritis. 

 A marked and similar difference was found in the size of the 

 right and left descending roots of the fifth nerve, and also in the 

 substantia ferrugiuea, the alleged nucleus of the so-called ti-ophic 

 root of the fifth nerve. This examination shows that, at least in 

 some cases of facial hemiatrophy, we have to do with a neuritis 

 of the fifth nerve. 



Such being the effects of trophic lesions in post-uterine life, 

 we have now to consider what evidence there is for any similar 

 affections occurring in the developing foetus. We know, unfor- 

 tunately, so very little about the directing causes of development 

 in the embryo, that all speculation of this nature must be some- 

 what hazardous. I shall now detail such cases as I have met 

 with, as seem to lend probability to such an action of the nerves 

 during development as I am arguing for. 



(1) I have first to revert to the exceedingly interesting remarks 

 made by Oakley Coles, in his chapter on the etiology of cleft- 

 palate, to which I have already referred, but which must now bo 

 more particularly considered. "The frequent association," ho 

 says, " of cleft-palate with defective development of the brain 

 has long been observed f, and various hypotheses have been put 

 forward to explain the connection. Thus, in the early part of 

 the century, Tiedemann J observed that in certain cases of cleft- 

 palate the nerves of smell are wanting or imperfectly formed, and 



* jSTeurol. Centralbl., July 15, 1888. 



t Leuckart, ' Untersuch. lib. den Zwischea Kiefer-Knocben des Menscben,' 

 Stuttgart, 1840. 



I Zeitscbr. f. Pbys. Ed. i. S. 71. 



