In 1842 Wilson brought out his extended systematic work on Diseases of the Skin, and subsequently produced twelve fasciculi of folio “Portraits of Diseases of the Skin.” In connection with these we may mention that he took a large share in the well-known five volumes of Anatomical Plates, issued jointly by Dr. Quain and himself. In 1843 he was elected a Fellow of the College of Surgeons, and in 1844 a Fellow of the Royal Society, having contributed to the latter a memoir on a newly-discovered parasite on the human skin, the _Entozoon folliculorum_. He made himself familiar with varieties of skin diseases by extensive vacation rambles—in Switzerland and the Valais studying goitre, in Italy searching out ringworm cases among the peasantry, in the East making leprosy a special object of inquiry. He wrote the article “Skin” in Cooper’s Surgical Dictionary, a Report on Leprosy, and many articles on various subjects connected with the specialty. Thus Wilson became a specialist of great merit as well as profitable practice, and, says the _Lancet_ (August 16, 1884), “knew more about skin diseases than any man of his time. He cured when others had failed to cure; and his works on dermatology, though they met with pretty searching criticism at the time of their appearance, have nearly all maintained their position as text-books. The horrible cases of scrofula, anæmia, and blood-poisoning which he witnessed among the poor of London—they are happily rarer now than they were half a century ago—enlisted his warm sympathies. But he had to deal with rich patients as well as poor, and over these the masterful stamp of his mind enabled him to exercise despotism in matters of diet. Wilson was not only a consummate dietician, but he knew how to make his patients submit to have their bodies placed under martial law.” He in fact largely viewed skin diseases as expressions of internal derangement and constitutional defects. He was continually on the look out for deficiency of nutrition in children and remedying it. Wilson was much pleased to be the means of bringing forward a little work on “Infant Life: its Nurture and Care,” written anonymously by a lady, and first published in his “Journal of Cutaneous Medicine.” In the preface which he wrote to it he expresses his strong beliefs that hygiene is the first necessity of a scholastic institution, that with proper nurture almost all the diseases of infants would be extinguished, that illness following vaccination properly performed can only occur owing to neglect of proper nurture and care, and that “healthy children never suffer, never die from vaccination.”