The development of the frog's egg; an introduction to experimental embryology

by Thomas Hunt Morgan

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 edition. ...the cells of the other side. It would seem then that even at the two-cell stage the axes of the future embryo are definitely laid down. But the most fundamental question remains unanswered; viz., has the egg after its first cleavage divided its material into qualitatively different parts (i.e. has the material of the right side of the body been separated qualitatively from that of the left side), or are the first-formed blastomeres still undifferentiated, and their subsequent fate dependent on the relative position they bear to each other as a part of a whole? Houx tried to answer this question by the following ingenious experiment. Roux's Experiment Of "Killing" Oxe Of The First Two Blastomeres As soon as the first furrow had passed through the egg, one of the resulting blastomeres was pierced with a hot needle. In order to carry out the experiment successfully, certain precautions must be taken. The eggs as soon as removed from the uterus are scattered over a glass plate (under water) so that they lie singly. Then water containing spermatozoa is added. After ten minutes this water, clouded by the spermatozoa, is poured off and fresh water is added. When the first furrow in the eggs appears, the water is again poured off. Each egg is held by a pair of forceps and then pierced by a hot needle. The needle is carefully sharpened, and is resharpened after each egg is operated upon. It is best to pierce the blastomere in the black hemisphere near the first cleavage-plane. The needle passes through about a half (or more) of the blastomere. When the needle is withdrawn, a greater or less amount of the contents of the blastomere protrudes where the blastomere has been injured. The egg after operation is returned to the water. It is necessary...

68 pages, Paperback

First published July 20, 2015

About the author

Thomas Hunt Morgan Ph.D. (Zoology, Johns Hopkins University, 1890) was an evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries relating the role the chromosome plays in heredity.

Morgan researched embryology during his tenure at Bryn Mawr College, the sister school of his alma mater. Following the rediscovery of Mendelian inheritance in 1900, Morgan's research moved to the study of mutation in the fruit fly Drosophila melanogaster. In his famous Fly Room at Columbia University, Morgan was able to demonstrate that genes are carried on chromosomes and are the mechanical basis of heredity. These discoveries formed the basis of the modern science of genetics. He was the first person to be awarded the Nobel Prize in Physiology or Medicine for his work in genetics.

During his distinguished career, Morgan wrote 22 books and 370 scientific papers, and, as a result of his work, Drosophila became a major model organism in contemporary genetics. The Division of Biology he established at the California Institute of Technology has produced seven Nobel Prize winners.