First work in English on experimental embryology.

Morgan demonstrated sex-limited inheritance.

In 1933 Morgan was awarded the Nobel Prize in Physology or Medicine "for discoveries elucidating the role that the chromosome plays in heredity." See also Nos. 245.3, 246, 13915.

Morgan proposed that what he called Mendelian factors (genes) are arranged in a linear series on chromosomes and that the degree of linkage between two genes on the same chromosome depends upon the distance between them. This fundamental idea enabled his student Sturtevant to map genes on chromosomes. (See No. 245.2).

Summarizes the major early findings of Morgan’s Drosophila research group, which based its research on the rapidly reproducing small vinegar fly, Drosophila melanogaster, often called the fruit fly. This epoch-making book presented evidence that genes were arranged linearly on chromosomes, and that the Mendelian laws could be shown to be based on observable events occurring in cells. The group also showed that heredity could be studied rigorously and quantitatively. Morgan was awarded the Nobel Prize for Physiology or Medicine in 1933.

Order of authorship in the original publication: Morgan, Sturtevant, Muller, Bridges.
Digital facsimile from Biodiversity Heritage Library at this link.

In this book Morgan first used the word gene. Previously he had used the term "Mendelian unit" or "factor." On the basis of genetic analysis Morgan presented a number of characteristics of genes:

1. A gene could have more than one effect. For instance, insects that had white-eye gene not only had white eyes, but al grew slower and had a lower viability.
2. The effects of the gene could be modified by external conditions, but these modiciations were not transmitted to future generations. The gene itself was stable; only the character that the gene controlled varied.
3. Characters that were indistinguishable phenotypically could be the product of different genes.
4. At the same time, each character was the product of many genes. For instance, 50 different genes were known to affect eye color; 15 affected body color, and 10 affected length of wing.
5. Heredity was therefore not some property of the 'organism as a whole,' but of the genes.
6. Genes of the pair did not jump out of one chromosome into another, but changed when the chromosome thread broke as a piece in front of or else behind them. Thus, crossing-over affected linked genes and groups, and was a product of the behavior of the chromosome as an entity.

Digital facsimile from Google Books at this link.