The discussion of Richard Goldschmidt and his saltational model of evolution is largely copied (without credit) from an essay by "creationist anatomist" David Menton. Goldschmidt's ideas were widely criticized when first publicized, and their reputation has not improved with time. There's no particular reason to cover them in a modern biology textbook at all.
It is difficult to be sure why Explore Evolution invests a full page in a discussion of Richard Goldschmidt's ideas. His work was rejected by biologists of his own day, and age has not improved his reputation. A recent assessment of his influence on modern biology concluded:
Richard Goldschmidt's research on homeotic mutants is not significant because it was right or paradigmatic. It is significant because it represents one of the first serious efforts to integrate genetics, development, and evolution. As such, Goldschmidt's research reveals the great difficulty of balancing the different contributors to a developmental evolutionary genetics. Consider the major flaws with his different models of macroevolution. Evolution by systemic mutations placed too much emphasis on a model of genetic structure which could not be confirmed or fully integrated with a model of gene action (not every inversion or chromosomal repatterning produces a phenotypic effect). Evolution by developmental macromutations placed too much faith in the ability of developmental processes to create functioning new species from major genetic changes. Goldschmidt needed [Sewall] Wright's counsel to provide a reasonable evolutionary dynamics for major mutations, which in turn made speciation by macromutation a possibility.Michael R. Dietrich (2000) "From Hopeful Monsters to Homeotic Effects: Richard Goldschmidt's Integration of Development, Evolution, and Genetics" American Zoologist 40(5):738 747
In short, Goldschmidt's erroneous ideas spurred other scientists to consider ideas which did ultimately improve our understanding of evolution. The insight that mutations could have both large and small effects influenced Sewall Wright's "shifting balance" evolutionary model a major component of modern population genetics. Similarly, evolutionary biologist Stephen Jay Gould wrote an essay on the "Return of the Hopeful Monster," in which he rejected most of Goldschmidt's actual argument, but identified useful insights which could guide modern researchers:
I disagree fundamentally with his claim that abrupt macroevolution discredits Darwinism. For Goldschmidt also failed to heed Huxley's warning that the essence of Darwinism the control of evolution by natural selection does not require a belief in gradual change.
[A]ll theories of discontinuous change are not anti-Darwinian, as Huxley pointed out nearly 120 years ago. Suppose that a discontinuous change in adult form arises from a small genetic alteration. Problems of discordance with other members of the species do not arise, and the large, favorable variant can spread through a population in Darwinian fashion. Suppose also that this large change does not produce a perfected form all at once, but rather serves as a "key" adaptation to shift its possessor toward a new mode of life. Continued success in this new mode may require a large set of collateral alterations, morphological and behavioral; these may arise by a more traditional, gradual route once the key adaptation forces a profound shift in selective pressures
In my own, strongly biased opinion, the problem of reconciling evident discontinuity in macroevolution with Darwinism is largely solved by the observation that small changes early in embryology accumulate through growth to yield profound differences among adults. Prolong the high prenatal rate of brain growth into early childhood and a monkey's brain moves toward human size. Delay the onset of metamorphosis and the axolotl of Lake Xochimilco reproduces as a tadpole with gills and never transforms into a salamander.
The element that Gould borrowed from Goldschmidt was not the erroneous view of genetics, nor Goldschmidt's model of how large morphological changes could be produced in that bogus genetic scheme. The connection between the sort of developmental biology research Gould describes and Goldschmidt's work is negligible. Hence Dietrich's observation above that the significance of Goldschmidt's work not being that "it was right or paradigmatic."
Neither Goldschmidt nor "hopeful monsters" is mentioned in the index to any of the most common college or high school biology textbooks. Evolutionary biology textbooks mention him only in passing, to note that his ideas were not and are not generally accepted. Ridley's Evolution merely observes that Ernst Mayr's arguments in favor of the Modern Synthesis won out against Goldschmidt's suggestions, and Futuyma rightly noting that Goldschmidt's genetic ideas "have been entirely repudiated by modern geneticists" and that his "saltationism was rejected in favor of gradual change" (even the changes Gould discusses above would be gradual in this sense). The lesson Futuyma draws from the coalescence of the Modern Synthesis, and the consequent rejection of ideas like Goldschmidt's, is that "the rejection of false ideas is an important part of the progress in science" (Futuyma, D., 1998, Evolutionary Biology, Sinauer Associates, Inc.:Sunderland, MA. p. 25).
In the perverted view of science promulgated by Explore Evolution, bad ideas never die. While there might be pedagogical value in leading students on a discussion of the flaws in Goldschmidt's ideas and the advantages of the Modern Synthesis, there is no value in the approach Explore Evolution takes. Simply tossing out a bad idea as if it were generally accepted today is unethical. Presenting an incomplete account of Goldschmidt, and leaving the impression that biologists today rely on his work, simply leaves students with the wrong impression.
An even worse impression will be left if students realize that the first paragraphs of Explore Evolution's page about Goldschmidt are copied without credit from another author. David Menton wrote those words for a young earth creationist group called the Missouri Association for Creation. Menton wrote:
In the 1930s, paleontologist Otto Schindewolf concluded that the missing links in the fossil record were not really missing at all, but rather were never there in the first place! Schindewolf proposed that all the major evolutionary transformations must have occurred in single large steps. He proposed, for example, that at some point in evolutionary history, a reptile laid an egg from which a bird was hatched! This bizarre notion was championed in 1940 by the geneticist Richard Goldschmidt of the University of California at Berkeley. Like Schindewolf, Goldschmidt resigned himself to the fact that true transitional forms were not found despite over a hundred years of searching for them, and that evolutionary theory would simply have to accommodate this fact.
Goldschmidt sought to advance Schindewolf's notion of evolution through single large steps by trying to imagine a plausible mechanism for it. He suggested that the answer might lie in what are known as embryological monsters, such as the occasional birth of a two-legged sheep or a two-headed turtle. Goldschmidt conceded that such monsters rarely survived very long in nature, but he hoped that over a long period of time some monsters might actually be better suited to survive and reproduce than their normal siblings. Goldschmidt named this monstrously hopeless speculation the "hopeful monster theory." Since there was not even the slightest shred of evidence to support the hopeful monster theory, it was dismissed with derision by almost all evolutionists of his time.
Compare this to the material in Explore Evolution (identical passages bolded, paraphrases in italics):
In the 1930s, paleontologist Otto Schindewolf proposed that all the major evolutionary transformations must have occurred in single, large steps. (He proposed, for example, that at some point in evolutionary history, a reptile laid an egg from which a bird was hatched.) In 1940, geneticist Richard Goldschmidt took Schindewolf's idea one step further, suggesting that true evolutionary change takes place in the rare successes of large-scale mutations, not by the accumulation of small changes (as Darwin predicted).
Goldschmidt conceded that the vast majority of large-scale mutations produce hopelessly maladapted freaks like two-legged sheep or two-headed turtles. However, he suggested that on rare occasions a lucky accident might produce a fundamentally new form of life an organism that was actually better suited to survive and reproduce than its "normal" siblings.Explore Evolution, p. 107
Teachers know that it is not appropriate to quote so much material from a source without proper credit. Paraphrasing a few passages and correcting some grammatical errors does not excuse the failure to identify the source. Not only does this passage misinform students about the current state of the science, distract from real science, and repeat creationist canards, it is also built on a serious ethical lapse. Students should not be sent the message that plagiarism is appropriate.