The dogma "omne vivum ex ovo," for the truth of which Harvey so justly con- tended against the fanciful notions of his age, cannot, perhaps, be now maintained in its integrity. Whether, to use an expres- sion of that day, living things are ever pro- duced automatically-that is, de novo- through putrefaction or otherwise, is, like the question of the limitation or universality of the germ power, still a matter upon which opinion is divided; and if it is my duty on this occasion to exhort you to investigate nature by way of experiment, I must ask you not readily to accept negative conclu- sions, which impose limits where none may really exist.
Still, it must be admitted that it is under the strictest and severest limits that nature does operate. If organization be automatic, it is so in a deeper and higher, in a wider and stricter sense than the mind of man hath as yet conceived. It is a process of whose beginning we have no knowledge or concep- tion, and the present facts of which must
