was concluded that the bias came from Gould, who failed to examine and remeasure the crania in order to determine Morton's level of accuracy. However, this study was reviewed in an editorial in Nature, which recommended a degree of caution, stating "the critique leaves the majority of Gould's work unscathed," and noted that "because they couldn't measure all the skulls, they do not know whether the average cranial capacities that Morton reported represent his sample accurately." The journal stated that Gould's opposition to racism may have biased his interpretation of Morton's data, but also noted that "Lewis and his colleagues have their own motivations. Several in the group have an association with the University of Pennsylvania, to whom Morton donated his collection of skulls, and have an interest in seeing the valuable but understudied skull collection freed from the stigma of bias and did not accept Gould's theory "that the scientific method is inevitably tainted by bias." A 2014 review of the paper by University of Pennsylvania philosophy professor Michael Weisberg, tended to support Gould's original accusations, concluding that "there is prima facie evidence of a racial bias in Morton's measurements". Weisberg concludes that although Gould did commit mistakes in his own treatment, Morton's work "remains a cautionary example of racial bias in the science of human differences". Research based on the discovery of some of Morton's original data by University of Pennsylvania anthropology doctoral student Paul Wolff Mitchell in 2018 argues that Morton was nevertheless guilty of bias, though not in data collection. Mitchell argues that Morton's interpretation of his data was arbitrary and tendentious; he investigated averages and ignored variations in skull size so large that there was significant overlap. A contemporary of Morton, Friedrich Tiedemann, had collected almost identical skull data and drawn conclusions opposite to Morton's on the basis of this overlap, arguing strongly against any conception of a racial hierarchy. Works “Observations on Cornine, (an Alkaline Principle, recently obtained from the bark of Cornus Florida, By George W. Carpenter of Philadelphia).” The Philadelphia Journal of the Medical and Physical Sciences 11 [n. s. 2]:195–198, 1825. “Description of the Fossil Shells characterizing the Atlantic Secondary Formation of New-Jersey and Delaware; including four new species.” Read on December 11, 1827 and January 1, 1828. Journal of the Academy of Natural Sciences of Philadelphia 6 (1): 72–73, 1829. “Geological Observations on the Secondary, Tertiary, and Alluvial Formations of