AS TO THE HEREDITY OF ACQUIRED COKDITIOISTS. 475 



ment, tried upon so large a scale, returns a negative reply is 

 indeed to my mind one of tlie best arguments against the 

 transmissibility of mutilations. There can be little doubt that 

 the recorded cases of congenital and bereditary edentulism 

 (congenital in the sense of the impotentiality being so) are blas- 

 togenic in their nature. 



Microphthalmus. — This is the first of a group of malformations 

 relating to the eye. In dealing witb them, I have to express my 

 obligations to my friend Mr. Priestley Smith, whose extensive 

 knowledge of ophtbalmological subjects has supplied my defi- 

 ciencies in that direction. Micropbthalmus is an hereditary 

 disease — Sedgwick * narrating a case where it was hereditary on 

 the maternal side and deaf-mutism on the paternal, both defects 

 co-existing in some of the unfortunate descendants. It is 

 extremely interesting in this connection to see how oj)inion as 

 to the cause of micropbthalmus has changed of late. It was 

 thought by some authorities, for example Deutschmann t, that 

 a foetal inflammation was the cause. Were this true the condi- 

 tion would be somatogenic. Quite recently, however, Hess J, 

 after a very careful examination of six microphthalmic eyes, has 

 concluded : — (1) that there was no sign of past or present inflam- 

 mation to be discovered; (2) that a union existed between the 

 vitreous and the outer tunics of the secondary optic vesicle 

 efl'ected by means of a tissue nourished by the hyaline artery or 

 a representative of that vessel. He goes on to state that he 

 cannot regard this as being in any way an inflammatory product, 

 but considers it to be the result of an atypical embryonic develop- 

 ment of the intruded mesoblastic layer which goes to form the 

 vitreous. He refers to other published cases which resembled his 

 in important respects, and to which lie is inclined to attribute a 

 similar causation. The connective-tissue band formed in these 

 microphthalmic eyes may possibly be related to the funiculus 

 sclerse, described by Hannover and shown by Eotholz to be the 

 permanent representative of a structure existing in foetal life. 

 Should these observations be correct, as seems highly probable, 

 the malformation is a blastogenic one, though it is perhaps 

 somewhat doubtful as to which class it should be referred to. 



* Med.-Chir. Eev. vol. xxviii. p. 20.5. 



t Klin. Monatsbl. f. Augenheilk., March 1881. 



I v. Graefe's Arch. f. Ophthalm. xxiv. 3. 



