I50 



HARD WJCKE'S SCIENCE-GOSSIF. 



that when the mite has only six legs it corresponds 

 with insects, whereas in its perfect state it belongs to 

 the spider family. Thus the mites "in this respect 

 connect the two great classes of Insecta and 

 Arachnida : " " Playtime Naturalist," pp 70, 170. 



"Wonderful! Wonderful!" exclaimed the com- 

 pany, though I believe they were all the time think- 

 ing more about the quality of the cheese than the 

 quality of my sermon, which must have been uncon- 

 scionably diy. However, I flattered myself that they 

 were interested, and proceeded. 



"This is not the only parcel that has been left 



Fig. 117. — Development of Tadpole seventeen days after 

 laying the egg. 



Fig. 118.— Eggs of Stone-mite. 



B 



Fig. iig.— Segmentation of Tadpole's esg. A, fourteenth day. 

 B, ditto, enlarged. 



behind," I continued ; and at a bound I passed from 

 the mite to the frog. Whether my hearers knew the 

 difference between a frog and a toad, I very much 

 question, but it is well to flatter your hearers some- 

 times by assuming that they know as much as your- 

 self, for no one likes to be considered a noodle, 

 though he may be the essence of stupidity. 



" Now," said I, "you know that when a frog's a 

 tadpole it's a fish 1 " 



"Never! Wonderful!" 



"It is wonderful, indeed," I continued; and 

 shameful as it must appear to the cool and philoso- 



phical outsider, I forthwith proceeded to preach a 

 second sermon on things left behind. How far I 

 succeeded I know not, but I endeavoured to show 

 that when a frog lays its spawn there comes forth 

 from each lump of jelly a tiny fish — scarce, if at all 

 different from the young begotten by a salmon or a 

 cod so far as the structure or anatomy is concerned — 

 with gills instead of lungs and a tail for swimming 

 instead of legs. I then showed how in due course 

 the fish was left behind, and the creature, while still 

 retaining its tail, improvised first one pair of legs and 

 then a second until it stood on a par with the newts. 

 Finally, I referred to the perfect animal, and showed 

 how it gradually absorbed its tail, until it stood before 

 us a beautiful and rational frog. 



My friends naturally wanted to know where all 

 this was leading, and I explained that such facts had 

 led the naturalist to theorize as follows : — Many 

 animals — and plants as well in a less degree — under- 

 go a series of changes in their progress from the germ 

 to the adult. At various stages they correspond to 

 animals whose development is complete — the larval 

 six-legged mite with the insect, and the larval tad- 

 pole with the fish — but eventually they pass beyond 

 these forms and assume others which are different and 

 higher. May not these stages indicate the lines along 

 which the creatures have moved in their race- 

 development ? Or to put the question in the 

 language of science, Does not the ontogeny of the 

 creature recapitulate its phylogeny ? {" Evolution," 

 by Le Conte, p. 9 seq.). 



I need scarcely say that mine host began to feel 

 that he was out of his depth, and I had to tow him to 

 land. This I did by explaining that so far as our 

 present knowledge goes the doctrine of evolution is 

 better adapted than any other which is at this 

 moment before the public to meet all the difficulties 

 associated with the questions of manifest life, while 

 its inabihty to deal with the origin of life, makes it 

 necessary for us still to revert to the Biblical doctrine 

 of a wise and beneficent Creator. 



NOTES ON NEW BOOKS. 



r) OPULAR LECTURES AND ADDRESSES 

 JL by Sir W. Thomson, F.R.S., &c., vols, i and 

 iii. (London : Macmillan). The all-embracing 

 science of modern physics owes more to Sir William 

 Thomson, perhaps, than any living man. Sir 

 William is not only an ingenious inventor 

 and a patient and accurate discoverer, but a born 

 teacher as well. As a lecturer he is too much in 

 earnest to stoop to popularity, and he is careless 

 about addressing any other than earnest students and 

 workers. He expects them to take a little trouble to 

 understand him, and they all know he is worth it. 

 Readers of these addresses must be prepared to 

 master a score or so of terms and phrases before they 



