Fresh-Water Rhizopods of North America (1879)

"Fresh-Water Rhizopods of North America" (1) was Joseph Leidy'slast monograph. (He continued to write shorter publications, primarily on parasites.) It contained 324 pages and 48 lithographic plates.

amoeba

Rhizopods are a group of single-celled (or acellular) organisms that are traditionally classified as protozoans (2). These microscopic organisms had been studied by European scientists since the time of Leeuwenhoek (3) , but this book effectively marks the beginnning of Protozoology in the United States.

Leidy limited his monograph to free-living, non-parasitic freshwater forms. Most of his rhizopods were collected from marshes, ponds and streams near Philadelphia, but others were collected from elsewhere in Pennsylvania and New Jersey, as well as from Connecticut, Rhode Island, the Bridger Basin (southwestern Wyoming) and in the vicinity of the Bay of Fundy in Canada.

The introduction to "Fresh-Water Rhizopods of North America" contains an overview of the group, which Leidy (and his scientific peers) regarded as the "simplest of all animals." He also takes the opportunity in the introduction to promote the use of the microscope as a research tool:

"The revelations of the microscope are perhaps not exceeded in importance by those of the telescope. While exciting our curiosity, our wonder and admiration, they have proved of infinite service in advancing our knowledge of things around us. The present work, founded on such revelations, I have attempted to prepare in a matter to render it easy of comprehension, with the view of promoting and encouraging a taste for microscopic investigations."

rhizopods Actinosphaeriumamoeba Hyalospheim difflugia
Four species from "Fresh-Water Rhizopods of North America" are shown above. Clockwise from the top they are: Amoeba proteus, Difflugia pyriformis, Hyalospheim papilio and Actinosphaerium eichhornii. Each image is a detail from a lithograph. Click on the images or the links above to view the lithograph.

Leidy expressed considerable frustration with the illustrations that graced his book. He did the original drawings (later copied to make the lithographic plates), but he regarded them as inadequate for representing the minature marvels he saw in the microscope. He was captivated by their complex movements, variable colors and ever-changing shapes.

Although Leidy was unsatisfied, the illustrations were cherished by others. Some of the drawings were preserved in bound volumes by Leidy's colleague and friend Joseph Willcox. Herbert S. Jennings, a leading American zoologist of the early 20th century, regarded Leidy as a scientific artist. He also regarded "Fresh-water Rhizopods of North America" as a "masterpiece" and " a section of nature permanently presented to us."

Four lithographic plates from "Fresh-Water Rhizopods of North America" (1879) are presented here:

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Websites:

  1. P.S. Neeley's page on Leidy (featuring more rhizopod images): www.xmission.com/~psneeley/Personal/Leidy.htm
  2. Tree of Life web page on Eukaryotes, including "Protozoans":
    tolweb.org/tree?group=Eukaryotes

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Notes:

  1. Fresh-water Rhizopods of North America. Vol. 12, Report of the United States Geological Survey of the Territories.
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  2. Protozoans (= first animals) is a group of single-celled organisms that have traditionally been regarded as animals. They are usually classified into four sub-groups: Flagellata (flagellates such as Euglena), Sarcodina (rhizopods such as Amoeba), Ciliophora (cilliates such as Paramecium), and Sporozoa (includes the malaria parasite Plasmodium). Their classification has been difficult because the group is extremely diverse. Scientists have long suspected that protozoans represent several very different evolutionary lineages. Recent studies have confirmed their multiple origins, but a satisfactory classification scheme is still being developed.
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  3. Antoni von Leeuwenhoek, the inventor of the microscope, first reported on protozoans in the 1670s, but the science of remained undeveloped until the 19th century. The most notable of these were Carl T. von Seibold, Rudolf Albert von Koelliker, Felix Dujardin and C. G. Ehrenberg.
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