The final quarter of the nineteenth century marked a turning point in the history of biology—biologists became less interested in applying an ideal of historical explanation deductively to organic function ⠀and more interested in discerning the causes of vital processes through experimental manipulation. But it is impossible to discuss the history of biology in the nineteenth century without emphasizing that those areas of biology most in the public eye had depended on historical explanation. Wherever it was applied, historical explanation was deemed causal explanation. The biologist-as-historian and the general historian of human events dealt with comparable phenomena and assumed necessarily a common mode of explanation.

Nineteenth-century biologists found a historical explanation of organic function attractive partly because their observation of the formation of a new cell from a preexisting cell seemed to confirm a historical explanation of cell generation. The same direct observation of continuous stages of development was also possible when they examined the complex sequence of events of embryogenesis. In both cases, the observer received a concrete impression that the daughter cell was brought into being, or caused, by the prior cell. The argument that these scientists employed confuses temporal succession and causal explanation, of course, but such confusion is the heart of most historical explanation.

Not surprisingly, the evolutionary biologists of the nineteenth century encountered a particularly troublesome problem in their attempts to document historical explanation convincingly: the factual record of the history of life on earth (e.g., that provided by fossils) was incomplete. The temporal continuity of living forms was convincing, but was an assumption that was difficult to uphold when one compared species or organisms forming any two stages of the evolutionary record. Nineteenth-century biologists recognized this problem and attempted to resolve it. Their solution today appears to be only verbal, but was then regarded as eminently causal. The fact
of evolution demanded some connection between all reproducing individuals and the species that they compose, as well as between living species and their extinct ancestors. Their solution, the concept of heredity, seemed to fill in an admittedly deficient historical record and seemed to complete the argument for a historical explanation of evolutionary events.

1. The primary purpose of the passage is to

A. compare the information about organic function made available by historical explanation with that made available by the experimental investigation of living organisms
B. assess the influence that theories of history had on developments in the field of biology in the nineteenth century
C. discuss the importance of historical explanation in the thinking of nineteenth century biologists
D. contrast biologists' use of historical explanation during the early nineteenth century with its use during the final quarter of the nineteenth century
E. evaluate the way in which the concept of heredity altered the use of historical explanation by nineteenth-century biologists



2. According to information presented in the passage, which of the following is a true statement about the methods of explanation used by biologists and historians in the nineteenth century?

A. Neither biologists nor historians were able to develop methods of explanation that were accepted by the majority of their colleagues.
B. The methods used by biologists to explain phenomena changed dramatically, whereas the methods used by historians to explain events did not change as noticeably.
C. Biologists believed that they had refined the methods of explanation used by historians.
D. Biologists' and historians' methods of explaining what they believed to be comparable phenomena were similar.
E. Although biologists and historians adopted similar methods of explanation, the biologists were more apologetic about their use of these methods.



3. Which of the following best summarizes the “turning point” mentioned in line 2?

A. The beginning of the conflict between proponents of the ideal of historical explanation and the proponents of experimentation
B. The substitution of historical explanation for causal explanation
C. The shift from interest in historical explanation to interest in experimentation
D. The attention suddenly paid to problems of organic function
E. The growth of public awareness of the controversies among biologists



4. The author implies that nineteenth-century biologists who studied embryogenesis believed that they

A. had discovered physical evidence that supported their use of historical explanation
B. were the first biologists to call for systematic experimentation on living organisms
C. were able to use historical explanation more systematically than were biologists who did not study embryogenesis
D. had inadvertently discovered an important part of the factual record of the history of living organisms on earth
E. had avoided the logical fallacies that characterize the reasoning of most nineteenth-century biologists



5. The passage would be most likely to appear in which of the following?

A. An essay investigating the methodology used by historians of human events
B. A book outlining the history of biology in the nineteenth century
C. A seminar paper on the development of embryogenesis as a field of study in nineteenth-century biology
D. A review of a book whose topic is the discovery of fossils in the nineteenth century
E. A lecture whose subject is the limitations of experimental investigation in modern biology