Pacf: Ten 



EVOLUTION 



October, 1928 



Tampering With Tadpoles 



By Joseph McCabe 



Cases that appear in the press occasion- 

 ally will have informed you that it is pos- 

 sible to graft flesh on a living body as 

 •well as to graft roses on cherry-trees. In 

 the fully formed body there are limits to 

 this power, but with embryos the most 

 amazing results can be obtained. We 

 can take two embryonic frogs, cut them 

 in halves and graft the head half of one 

 on the tail half of the other. This can 

 be done even when they are of different 

 species and different colors, and the frog 

 which they then form is a very curious 

 creature. We can cut out from the embryo 

 of a newt a part of the skin which ought, 

 in ordinary development, to form a nerve, 

 and graft on to the place a group of the 

 cells which form ordinary skin, and the 

 newt will develop no nerve at that spot. 

 We can cut a piece out of the embryo and 

 turn it round, and the newt, when it is 

 fully formed, will have that patch of its 

 anatomy entirely misplaced. Its eyes, for 

 instance, will be on its back, and the back 

 part where the eyes ought to be. We can 

 make the ears grow upside down. We 

 can take the first rudiments of the legs 

 and graft them on the side of the head, 

 and they develop there just as they would 

 in their proper place. I do not say that we 

 can take any organ and make it grow 

 anywhere, but in the case of an embryo 

 in an early stage of development there is a 

 most amazing power of transferring organs 

 in this way. The "vital force" people must 

 imagine that their architect has lost his 

 head under the knife, so to say. 



A still more curious series of experi- 

 ments has been tried. When the embryo 

 of a chick is developing in the egg it is 

 surrounded by a membrane, and someone 

 got the idea of grafting bits of other em- 

 bryos on this. The budding limbs, for in- 

 stance, of one chick embryo have been cut 

 ofi' and grafted on the outside of the mem- 

 brane enclosing another embryo, and they 

 develop there. In short, almost any organ 

 can, in its rudimentary form, be detached 

 from an embryo and made to grow on the 

 outside of another embryo. Eyes, noses, 

 ears, and even internal organs have grown 

 in this totally unnatural medium. Wlien 

 the eyes or limbs or other organs are re- 

 moved from an embryonic chick, the part 

 of the brain which ought to deal with 

 the working of the missing organ does 

 not develop. 



Thus embryologists are now convinced 

 that what we call life is not some mysteri- 

 ous thing that belongs to the body as a 

 whole but that each little group of cells 

 has its own life. Most of us suppose that 

 any part cut away from an organism loses 

 its share of the "life" of the organism 

 or can live no longer. This is found to be 

 quite untrue as far as the embryo body is 

 concerned. We can cut out a bit of the 

 tissue from one of the organs, even the 

 heart or the kidneys, and that group of 

 cells will continue to live and grow; if, of 



course, it is kept in the proper conditions 

 to feed and maintain it at the hight temper- 

 ature. In the warm fluid m a little glass 

 tube the heart of the embryo chick, or 

 even a section of the heart, will continue 

 to beat long after it has been cut away 

 from the body. These experiments were 

 started more than ten years ago, and they 

 have already proved a remarkable truth: 

 it is that not only can parts of the body 

 be kept "alive" when detached from it, 

 but they will live a longer time in their 

 isolated condition than they would in the 

 body itself. Sections of the heart of an 

 embryonic chicken have been kept alive in 

 a tube for ten years, which is more than 

 the life of a fowl. 



Other series of experiments show the 

 profound influence of environment on the 

 developing body. Concentrated sea-water 

 and other fluids will cause the develop- 

 ment of an ovum which has never been 

 fertilized, and some chemicals have curi- 

 ous effects which are quite unintelligible. 

 We take, for instance, the eggs of a certain 

 fish — not any fish — and let them develop in 

 a solution of magnesium chloride instead 

 of sea-water. When the body of the fish is 

 fully developed, it is found to have one eye 

 in the center of its forehead instead of a 

 pair. Tadpole embryos in other chemical 

 solutions have their eyes developed deep 

 under the skin. All kinds of modifications 

 of organs are caused by changing the 

 chemical composition of the fluid in which 

 the embryo is developing. 



Some curious experiments in diet throw 

 further light on this influence of the en- 

 vironment. The importance of the thyroid 

 gland is well known, but its effect in the 

 frog world is remarkable. If the extract or 

 secretion of the thyroid gland be fed to 

 tadpoles in an early stage they start at once 

 to develop into frogs. The time these "doc- 

 tored" tadpoles take to become little frogs 

 is only about one-tenth the usual time. On 

 the other hand, if the thyroid is removed 

 from a tadpole it never becomes a frog. 



In short, tens of thousands of experi- 

 ments have been made on embryos, and 

 the embryologist today finds that he can 

 at will produce the most weird and won- 

 derful forms. He can drug an ovum, and 

 cause it to admit a sperm-cell of an ani- 

 mal of a different species and so make 

 hybrids. He can make half animals or 

 quarter animals or compound animals. He 

 can cut an embryo into pieces and keep the 

 pieces alive in so many glass tubes, the 

 cells feeding, growing and multiplying just 

 as if they were in what we call the living 

 body. I should be inclined to say that he 

 has proved that there is no such thing as a 

 vital force or principle, for, clearly, such a 

 thing could not possibly be divided. 



JOSEPH McCABE 



There may be a few of our readers who 

 do not yet know of Joseph McCabe, who 

 is to lecture under the auspices of Evolu- 

 tion, so here's a little introduction. 



Joseph McCabe was born in England 

 in 1867. Trained in various English schools 

 and Louvain University. Was Franciscan 

 Monk, 1883; Priest, 1890; Professor of 

 Philosophy, 1890-1894; Rector Bucking- 

 ham College, 1895. Left Church, 1896. 

 Ever since then, for over thirty years, he 

 has been writing and lecturing on ration- 

 alist, scientific and historical subjects in 

 all the important countries of the world. 



Among his writings of over one hundred 

 volumes are: Twelve years in a Monastery, 

 History of the Jesuits, Modern Rational- 

 ism, Principles of Evolution, Evolution of 

 The Mind, A. B. C. of Evolution, Story 

 of Evolution, The Ice Ages, and over fifty 

 of the little Blue Books. He is also the 

 author of The Key to Culture, a forty 

 volume series published by Haldeman- 

 Julius, an outline of all human knowledge. 



McCabe is known on three continents 

 as "The World's most learned Man", but 

 his constant effort in his writings as well 

 as his lectures has been to make this vast 

 learning available and understandable to 

 the ordinary man. 



This year Joseph McCabe is lecturing 

 in Canada, finishing his tour early in Jan- 

 uary on the Pacific coast. He has kindly 

 consented to fill a limited number of lec- 

 ture engagements under the auspices of 

 Evolution on his return trip East through 

 the United States. Those that already 

 know him will need no urging to write 

 for a date. Fundamentalists recognize in 

 him their greatest foe, evolutionists their 

 strongest champion. A lecture by McCabe 

 will mean a mental awakening for your 

 entire community. 



Teacher: "What is the spinal column?" 

 Little Johnnie in the back seat: "It's 



a bone what runs up and down your back. 



Your head sits on one end, and you sit on 



the other." 



A CORRECTION 



Dr. J. A. Maryson of New York has 

 kindly called attention to an error that 

 crept into last month's article on the 

 •'Circulation of the Blood". It spoke of 

 the red corpuscles as "boats of the blood 

 stream carrying food matter and oxygen 

 to the body tissues and carrying away the 

 wastes." The fact is that, though the 

 blood stream does carry food and wastes, 

 the corpuscles carry only oxygen. In con- 

 densing this distinction was left out. The 

 red corpuscles contain a substance called 

 haemoglobin which unites loosely with 

 oxygen in the lungs and turns red (being 

 then called oxyhaemoglobinK When the 

 corpuscles get into the body tissues, a 

 difference in condensation causes the re. 

 lease of the oxygen which is then used up 

 in the slow combustion which supplies en- 

 ergy to the living cells. The haemoglobin 

 of the corpuscles then goes back to the 

 lungs for another supply of oxygen. 



We wish to thank the doctor for hir 

 correction. We are trying to keep Evolu- 

 tion free from scientific errors and ap- 

 preciate the help which our readers may 

 render by calling attention to mistakes. 



