Francesco Redi, an Italian physician, proved as early as 1668 that higher forms of life did not originate spontaneously, but proponents of abiogenesis claimed that this did not apply to microbes and continued to hold that these could arise spontaneously.
This chapter is particularly sore for Spiritists because it actually accepts spontaneous generation as fact: a phenomenon that took place every day (which was according to mainstream scientific thinking of that time, only to be displaced decades later by the work of Louis Pasteur).