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and, furthermore, that the first processes of grovrth, and many of the subsequent 

 modifications, are essentially the same in principle in almost all." Now, what 

 is xhis original starting point? It is a single vesicle of miniite size, with a 

 still smaller nucleus in its centre ; and for a short period the development 

 proceeds in parallel lines. There is a wonderful difference between a spaiTOW 

 and a cat that would eat it, but there is a i)eriod in the embryonic development 

 of the sparrow when I would defy you to be able to say whether the embryo 

 sparrow would turn into a bird or a mammal, supposing, of course, you had no 

 knowledge of the source where the embi-yo was derived. I will instance this 

 by an example that came under my own notice a short time ago. A swallow's 

 egg was brought to me, and on breaking it and placing its contents in a saucer 

 of water, I discovered an embryo about four lines long and 1 or l.J lines broad. 

 After detaching it from the yelk by dividing the umbilical vessels, I placed it 

 in a small flattened glass tube filled with clear water. I showed it the same 

 evening to five or six gentlemen who were dining with me, and asked one after 

 the other if he could tell to what animal the embryo belonged ? Well, various 

 guesses were given : one thought it was the embryo of a dog, another of a mole, 

 another thought it was that of a lobster. At last I asked whether they were 

 quite sure it did not belong to some bird ? A chorus cf negatives followed my 

 query ; whatever the embryo was, it certainly was not that of any bird. And 

 certainly the embryo would remind anyone rather of a mammal than of a bird ; 

 the head had assumed as yet nothing ornithic about it ; the wings were repre- 

 sented by two anterior cylindrical processes, the legs by two similar posterior 

 processes, scarcely distinguishable from the former ; at the end was a single 

 process representing the tail. Nor, indeed, can experienced Naturalists distin- 

 guish embryos at certain periods of their development. Von Baer, to whom 

 science is so much indebted, says : " In my collection there are two little 

 embryos which I have omitted to label, so that now I am quite incompetent 

 to say to what class they belong. They may be lizards, they may be small birds, 

 or very young mammals ; so complete is the similarity in the mode of formation 

 of the head and trunk. The extremities have not yet made their appearance. 

 But even if they existed in the earliest stage, we should learn nothing from 

 them, for the feet of lizards, mammals, and the wings of birds will arise from 

 the same common form." Agassiz examined more than a hundred species of 

 bird-embryos, and found that at a certain period they have all bills, wings, 

 legs, feet, &c., exactly alike. The young robin and the young crow are web- 

 footed as well as the duck." I can testify to the fact of the yovmg embryo 

 of the blackbird being web-footed, and probably this is the case with most 

 birds. Now the embryology of birds can be pretty readily observed, and I hope 

 that another year some members of the 'Woolhope Naturalists' Field Club — a 

 club that evidently means work, and assembles at its different meetings for 

 practical scientific purposes, and not for picnics — will turn their attention to 

 ornithic embryology, and make collections of embryos of different birds at 

 various periods of their development. 



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