After a careful comparison of the symptoms of the Solanum tuberosum ægrotans with those of the other known remedies of our Materia Medica, we have found them to agree with the symptoms of the following drugs which we enumerate in the order of their importance: 1. _Bryonia_; 2. _Arsenicum_; 3. _Plumbum_; 4. _Nux-vomica_; 5. _Sepia_; 6. _Strontiana_; 7. _Viola-tricolor_; 8. _Squilla_; 9. _Pulsatilla_; 10. _Graphites_; 11. _Alumina_; 12. _Mercurius_; 13. _Natrum-mur_; 14. _Ignatia_; 15. _Calcarea_. We have no doubt that Bryonia and Arsenicum will prevent the rot; but, to be frank, we believe that, in this case at least, the isopathic method of treatment will prove more successful than the homœopathic. It is well known that the mode of preparing our drugs for medicinal purposes, modifies their action a good deal. This result is principally obtained by rubbing them down with sugar of milk, which is not an inert substance as Hahnemann believed, but is on the contrary endowed with the most useful powers of action. The sugar of milk effects a preliminary digestion of the drug, and, by imparting to it vital qualities, fits it for medicinal purposes. Do we not know that certain animal products are preferable to corresponding mineral substances? Is not the calcarea prepared from the oyster-shell preferable to the chemically prepared carbonates and phosphates of lime? Are not the poisons of serpents destined to occupy the first rank among the polychrests? To return to our subject, the medicinal preparation obtained from the diseased potato is not the original poison as used by nature, but the poison modified in consequence of its having been previously engrafted on a living tubercle. Our mode of inoculating either the isopathic or homœopathic preparation is as follows. Before putting the potato in the ground we perforate it with a big needle, and into this hole we insert a single globule of the third attenuation. This operation is simple and easy. It can be applied on a large scale and we think that by its means the potato will be preserved for a long time yet to the European continent. First prover: _Van-Dyck_, 26 years old, of a sanguine nervous temperament and a robust constitution. _First day._—1. Painful stitch in the right side, a few moments after taking the drug. Acidity and eructations, at 9 in the evening. _Second day._—On waking, weight above the eyes and in the forehead, as the morning after being intoxicated. Shuddering and sensation of cold internally, at noon. 5. Scanty and difficult stool, in the shape of small hard balls, in the evening.