Wells was perhaps the greatest of the pioneer ovariotomists; he performed his first ovariotomy in 1858. The title page to this work states that a second volume would be published. By the time Wells issued the intended Volume two he considered it an entirely separate work and not a continuation of his 1865 treatise. The second work, published in 1872, has frequently been miscatalogued as Volume two because it bears the same title and was issued by the same publisher. However, it is not called Volume two on its title page.