Vastly more important than the multitude of general social and economic facts are these statistics of what, for want of a better term, may be called _human production_, and which disclose what must be considered the most alarming tendency in American life. Granting that excessively large families are not desirable, at least from an economic point of view, it cannot be questioned that the diminution in the average size of the family, and the increase in the proportion of childless families among the native-born stock is evidence of physical deterioration, and must have a lasting and injurious effect on national life and character. Section IV. Medicine and Eugenics. THE PROPHYLAXIS OF HEREDITARY SYPHILIS AND ITS EUGENIC EFFECT. (Abstract.) By Dr. H. Hallopeau. Syphilis is strongly _dysgenic_; it causes the production of profoundly damaged children; in preventing it the physician co-operates effectively with eugenic action. In order to prevent the propagation of this disease we must have recourse to _administrative prophylaxis_, _prophylaxis by persuasion_, and _prophylaxis by medical measures_. _Administrative prophylaxis_ must act especially by multiplying gratuitous consultations and in securing, as far as possible, hospital treatment for persons affected by transmissible lesions, especially for prostitutes. To the physician belongs the duty of acting by _persuasion_ in pointing out to syphilitics that they have no right to have children so long as they are liable to transmit their disease to their offspring. We must abort syphilis if it is in the stage of primary invasion: this invasion is not, as was believed until recently, confined to the chancre and its accompanying swellings; it includes all the intermediate stage; in order to destroy the tripanosomes we must use repeated injections of _benzosulfoneparaminophenylarsinate of soda_, commonly known as _hectine_ (Mouneyrat), the only specific medicament which is well borne locally. Results similar to those we have just shown are obtained by making, in a given region, two or three injections of salvarsan. However, the comparison between the two medications is altogether in favour of that by hectine. Indeed, experience proves that the secondary generalization is noticeably more frequent after injections of salvarsan, and, besides, these are far from being always painless. We have made known to the Académie of Medicine a case in which, within 48 hours, they caused the death of a young man in good health. Several similar cases have since been notified, particularly by Dr. Gaucher. Confidently believing in the axiom "Primo non nocere," we explicitly declare ourselves adversaries of a practice which brings such accidents in its train. In the secondary stage, we must have recourse simultaneously to various specific agents. Procreation may be permitted when six months after the abortive treatment Wasserman's reaction, after several trials, has given uniformly negative results.