There are some minds that stop short at what they first perceive, others that continue to observe phenomena to make deductions, and arrive at conclusions. When, however, imagination is very active the observer may tire of the monotony of incessant, repetitive study, and after establishing a certain number of proofs leave other cases unfinished, or divert the evidence to a fantastic end, and asin against philosophy ), or logic. Something of this kind may account for the strange suspension of judgment in REDI'S observations, where in his experiment with the larvae in the oak-gall, he attributes their death in the gall to the fact that it was detached from the tree, and thus deprived of contact with the vital force inherent in the living plant. Such an admission exposed him to the sarcastic criticism of VALLISNIERI, a physician also, but of a later, and more sceptical time, who boasts of ((our Century of Science v>, the eighteenth, and writes condescendingly of the efforts to combat the theory of spontaneous generation in the seventeenth century. In fact he repeats REDI'S oak-gall experiment, and shows why it failed in his treatise on the garden rose sawfly, which was selected for the translation that follows to serve as a sequel to the Experiments on the Generation of Insects by FRANCESCO REDI, previously translated. (I)