644 [December 



duced, are not born in the manner which, so far as I am aware, is uni- 

 versal with all viviparous animals, but eat their way out of the body of 

 the so-called mother-insect. This alone is an anomaly, which, if there 

 were no other reason to discredit Wagner's theory, would tend to involve 

 it in the gravest suspicion. But to dwell on minor points like these is 

 useless, and seems like straining at a (Inat and swallowing a Camel. 

 Those that reject as incredible the fact of the existence of procreative 

 larvae, and of distinct species of one and the same genus procreating in 

 two widely distinct and heterogeneous manners, do not need such argu- 

 ments ; and those that have sufficient fiith to digest these startling ano- 

 malies, are beyond the reach of pop-guns, and can be effectually attacked 

 only by cannon of the very largest calibre. 



If it were not almost a work of supererogation to quote examples of 

 grievous mistakes made by scientific men, and adopted and believed in 

 for a long time by other scientific men, I might instance the well-known 

 experiments of Cross, which were supposed to demonstrate, that a certain 

 species of Mite (^Acarus~) was generated spontaneously, or in plain 

 English created, by the hands of the manipulator. Yet who at the 

 present day believes that Mites can be created by Man ? I might in- 

 stance also the conclusion arrived at by Rudolphi in his latest work on 

 Entozoa (Intestinal Worms), viz. that these animals, or some of them 

 at all events, must be spontaneously generated, because he demonstrates 

 at great length the impossibility of their being normally generated in 

 any one of what seemed to him all the possible modes. He little 

 thought, when he announced this startling conclusion, that it would 

 hereafter be proved, that what he considered as distinct families of En- 

 tozoa, were merely the larval forms of other families ; and that the 

 small, bladder-like worm from the liver of a hog could pass in+o the 

 human body and become metamorphosed into twenty yards of Tape- 

 worm. I remember well that, thirty years ago, the veteran geologist 

 Prof. Sedgwick, when I informed him of the conclusions at which Ku- 

 dolphi had arrived, remarked to me that he would not believe in them, 

 even if a hundred eye-witnesses were to testify to the truth of the facts 

 upon which those conclusions were based. 



