AS TO THE HEUEDITY OF ACQUIRED CONDITIONS. 495 



of talipes, he says, " The question of their origin from irregular 

 muscular contraction is still an open one ; buc the arguments in 

 favour of this view are exceedingly strong." Messrs. Parker and 

 Shattofk, as has before been mentioned, take a different view as 

 to the etiology of the condition. In their specimen it is true 

 that a microscopical examination revealed no lesion in the central 

 nervous system; at the same time it is a matter for argument 

 whether this is proof positive that no nervous influence was con- 

 cerned in the production of the condition. It seems to me at 

 least possible that some temporary stimulus, say of a chemical 

 nature, might set up irregular contractions in the muscles, without 

 any changes resulting in the nervous system. We kuow that 

 drugs admiuistered to the mother can affect the foetus, and the 

 same may be true of other chemical stimuli of Avhich we may know 

 little or nothing. If this be true, the resulting lesions would be 

 somatogenic in their nature ; but we are at present in ignorance 

 as to whether, in the first place, all lesions which are attributed 

 to this cause are really due to it, or whether some of them may 

 not follow upon a lack of material, as seems probable, in which 

 case they would be blastogenic in their nature. And, secondly, 

 supposing that these lesions owe their origin to more than one 

 cause, we have no method, at present, of distinguishing between 

 the two or more classes. Here, as in many other instances, it is 

 much to be hoped that teratological workers will direct, in the 

 future, more attention to the cauisation of malformations, so that 

 these and other cognate problems may be cleared up. 



Section Y. — Heeeditaby Disease. 



The subject of hereditary disease is one which should not be 

 neglected in an inquiry of this kind. I pnrpose, therefore 

 devoting a few lines to this subject in its connection with the 

 present topic. 



The greatest confusion has been introduced into the contro- 

 versy on acquired characters by some who have mixed uij the 

 various kinds of hereditary diseases, which fall into classes of 

 the most divergent nature, with one another and with hereditary 

 variations and malformations. It will, then, be advisable to state 

 what are the groups of hereditary diseases considered in relation 

 to the present inquiry. 



