2a. The main point determined by modern investigation into the action of silver compounds is their special effect on the nervous system. The best experiments on animals have been made by hypodermic injection of hyposulphite and albuminate of silver, which do not coagulate albumen. Charcot and Ball found paraplegia result from such injections (Gaz. Medorrhinum, 1864). Rouget found that in mammalia small doses caused excitement somewhat like that of strychnia; toxic doses induced convulsion and asphyxia. Batrachians got convulsions or tetanic spasm with suspension of voluntary movements, of reflex action, and of respiration, while circulation continued; weakness, torpor, somnolence and paralysis also occurred in various degrees (Arch. de Phys., 1873). Curci found hypodermic injections of the hyposulphite first stimulate the sensory nerves, and through them the posterior columns of the cord, so that impressionability and reflex excitability are increased; this condition extends more or less to the motor nerve-tracts, muscular irritability is heightened, and tetanus may be produced; afterwards comes a secondary paresis of sensory nerve-centres and of those connected with respiration; ultimately reflex action is arrested, and respiration and circulation cease. (Lond. Medorrhinum Record, 1877).
2b. Orfila described asphyxia as resulting from injecting silver nitrate into the veins, and after death he found partial consolidation of the lungs, and excessive secretion into the bronchial tubes. Several observers have corroborated these results, and it has been a question whether they are mainly mechanical, from thrombosis, &c., or due to a reflex paresis of the pulmonary nerves, as maintained by Charcot (who found the bronchorrhea and asphyxia result from hypodermic injection), or results of direct action on the respiratory centre in the bulb and of the neighbouring vaso-motor centre. The recent observations of Rouget point to the latter conclusion. He found that in most animals urgent dyspnoea occurred, and, post mortem, the lungs proved to be healthy in texture but much contracted in volume-the muscular tissue of the bronchi being in a state of spasm similar to that of asthma. In adult specimens of only one order of animals (carnivora) did he find the excessive secretion described by Orfila, and he considered that only in these were the vaso-motor centres affected. That the main effect is exerted upon the central rather than on peripheral nerve-element he further supported by showing that nerves and muscles retained electric excitability after death. Still more recent observations by Rozsahezzi (Archiv, Klebs, Aug., 1878.) on rabbits show that in chronic poisoning by silver there is constantly hyperemia of laryngeal and tracheal membranes, also of the lungs, and in these organs often edema was found, with congestion, ecchymoses, effusions, cheesy masses, and sometimes a condition resembling phthisis.
2c. Rozsahezzi also found very marked diminution of tissue change and of weight, under the continued influence of small doses of the nitrate. This occurred even whilst the animal was taking a good amount of food, and when no increased exertion could account for the loss; he thinks it indirect, from impaired blood-and muscle-condition. (PHILLIPS, op. cit., sub voce.) [ “In man, even after the administration of large doses of silver nitrate, none of the above-mentioned symptoms or organic changes have been met with” (NOTHNAGEL and ROSSBACH).
Hughes was a great writer and a scholar. He actively cooperated with Dr. T.F. Allen to compile his 'Encyclopedia' and rendered immeasurable aid to Dr. Dudgeon in translating Hahnemann's 'Materia Medica Pura' into English. In 1889 he was appointed an Editor of the 'British Homoeopathic Journal' and continued in that capacity until his demise. In 1876, Dr. Hughes was appointed as the Permanent Secretary of the Organization of the International Congress of Homoeopathy Physicians in Philadelphia. He also presided over the International Congress in London.