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Models of Frog Embryological Development (Mueller Ward)


A set of eleven plaster models mounted on wooden bases, each representing a stage in the development of the frog embryo. These examples are not brightly coloured like those represented in 2023.zoo.80.1-11 and 2023.zoo.81.1-7. They appear to be primarily focused on the external form.

This set is similar to 2023.zoo.82.1-21, which is catalogued in detail. Unlike the other sets of this type, 2023.zoo.82.1-21 and 2023.zoo.83.1-21, the models of this type are set on round rather than square bases. The models in this set are labeled with an “C” written on the paper table label applied to each model. This set has one less model than 2023.zoo.82.1-21.

Accession Number: 2023.zoo.84.1-20

Alternative Name:

Primary Materials: Plaster, Wood.


Dimensions (cm):

Diameter of the round base = 10. Typical height of a model is ~14. The longest model is 31.


These models represent the stages of embryological development of the frog, an organism commonly used in biological instruction.

A c. 1945 Mueller-Ward catalogue notes the following: “The models are not meant to supplant the actual study of the frog’s egg itself, but only to give the student certain definite ideas and a few clear landmarks so that this study may be rendered easier and more profitable.”


The paint of most of the models has been chipped with use, especially around exposed edges. It is not clear whether this set is complete.

Associated Instruments:


Ward’s Natural Science Establishment, Inc., Rochester, NY.

Date of Manufacture: Mid 20th Century.


These models were used at the Department of Zoology (now part of the Department of Ecology & Evolutionary Biology and the Department of Cell & Systems Biology).

The models were photographed and catalogued on Feb 6, 2023. They remain at the Department of Ecology & Evolutionary Biology.

Additional models of this type are located in the EEB teaching lab, so the sets catalogued here may be incomplete.

Additional Information and References:

A brief biography of Justus F. Mueller (1902-1993), the developer of the models, can be found at New York Heritage Digital Collections, along with information on his personal papers at SUNY Upstate Medical University – Health Sciences Library. (Archived February 13, 2023).

Some relevant digitized catalogues can be found at “The Ward Project” website that is run by the University of Rochester. See especially Mueller-Ward models of frog embryology (c1945). (Accessed March 7, 2023)

A brief history of Ward’s Natural Science Establishment, Inc., which produced the models, can be found at the River Campus Libraries of the University of Rochester. This archive holds the company’s papers. (Archived February 13, 2023).

Historical Notes:

The models in this collection were developed by Justus F. Mueller (1902-1993), an American parasitologist educated in both art and zoology. Following his graduate research at the University of Illinois, Mueller took a position at the New York State College of Forestry (now SUNY College of Environmental Science and Forestry) in Syracuse, New York in 1929.
While at the College of Forestry, he partnered with Ward’s Natural Science Establishment, Inc. to create 16 sets of zoological models comprising 116 models.

Ward’s Natural Science Establishment was founded in 1862 by Henry Augustus Ward (1834-1906). The company supplied natural science materials to museums. In 1928, the Ward family donated the company to the University of Rochester. The company began to flourish in the 1940s and was sold to Dean L. Gamble, its president, and Frank Hawley Ward in 1940. The company became very successful during the expansion of science education in the early Cold War Period.