Microscopic examination of the tracheal dimensions of normal Florida mice (Peromyscus floridanus) and cotton mice (P. gossypinus) showed no significant differences between the two species, but external examination showed the tracheal length of the Florida mouse to be longer than that of the cotton mouse. Microscopic examination of the intrapulmonary apparatus (bronchioles, alveolar ducts, atria, and alveoli) of normal Florida and cotton mice showed no significant differences in measurements between the two species. Cotton mice were exposed to exhaust gases produced by the burning of solid rocket motor (SRM) fuel. Mice exposed once for a duration of 10 min demonstrated an LD50 of 52 to 56 ppm HCl/g body weight and an LD50 of 169 to 173 mg Al2O3/m3/g body weight. These LD50 values suggested that SRM exhaust components may have a synergistic lethal effect when compared to the effects of individual components of the exhaust. Cotton mice exposed to the exhaust exhibited external signs of respiratory distress and dyspnea. Those mice that received lethal exposures showed internal signs of early inflammatory reactions. However, the most likely cause of death was a sudden shift in blood pH.

Thesis (M.S.)--Ohio State University. / Bibliography: leaves 40-42. Available online via OhioLINK's ETD Center

No description available.

Thesis (Ph. D.)--University of Michigan, 1939. / Cover title. "Reprinted from the Journal of experimental zoology, volume 83, number 1, February 5, 1940." eContent provider-neutral record in process. Description based on print version record. "Literature cited": p. 58-60.

Thesis (M. Sc.)--Carleton University, 1988. / Also available in electronic format on the Internet.

Thesis (M. Sc.)--Carleton University, 1997. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Michigan, 1939. / Cover title. "Reprinted from the Journal of experimental zoology, volume 83, number 1, February 5, 1940." "Literature cited": p. 58-60.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The object of this study was to compare the role of changes in reproduction and mortality in regulating population density in the deer mouse, Peromyscus maniculatus, and if possible to discover some of the factors affecting the reproductive rate. Observations were made on natural and experimentally reduced populations on the University Endowment Lands in 1964 and 1965. In both years numbers remained relatively steady during the summer, increased in the fall, when immature animals replaced the adults, and gradually declined over the winter. Animals were about equally abundant at comparable times in both years, fall densities being about 4.72 mice per acre. The stationary state of these populations was associated with a poor reproductive performance on the part of the females, whose breeding success varied between areas, and was greater in 1964 than in 1965. No change in litter size or in prenatal loss was observed during the period of study. The males, in contrast, were sexually active from March to September on all areas in both years. The greatest loss of mice occurred between birth and age at first capture, after which juveniles survived at the same rate as the adults. Survival was poorer during the breeding season than during the winter, and survival of males was poorer than that of females. Populations whose numbers had. been experimentally reduced and whose age structure had been altered, were not significantly different from the natural populations in mean monthly body weights, reproductive performance, or survival. Mean monthly body weights and reproductive performance were lower, and survival of the young from birth to age at first capture was higher in 1965 than in 1964. The proportion of subadults which became fecund was greatest on this area in 1964. The stationary state of these populations was maintained by changes in survival rather than by changes in reproductive rate. The reproductive performance of the females was fairly constant whereas the loss of young from birth to age at first capture varied. Loss of the young is attributed to their death or emigration in response to aggressive interactions within the population. / Science, Faculty of / Zoology, Department of / Graduate

Sadleir (1965) proposes that the survival of juvenile deermice is determined by the aggressiveness of the adult population. During the summer, when adult aggression is high, juvenile survival is poor, but in the fall, when adult aggression is low, juveniles survive well. The purpose of this study is to examine some of the consequences of Sadleir's hypothesis experimentally. Sadleir bases his hypothesis on the observation that the aggressiveness of males changes seasonally. This premise has been reexamined and confirmed. How adult aggression affects juveniles was studied first in the laboratory. Juveniles grow poorly when competing with adults in their home cage. Males appear to be more active aggressors than females, but only aggressive males are capable of inhibiting juvenile growth. Even though juveniles grew slowly when competing with aggressive adults, they seldom died from encounters with adults. In order to avoid the crowded conditions and confinement implicit in the laboratory experiments, the relationship between adult aggressiveness and juvenile growth and survival was reexamined in field experiments. Two partly isolated plots of habitat were used, and on these plots artificial populations of aggressive or docile male deermice were established. Juveniles were then released onto the plots, and their growth and survival followed. In the field, as in the laboratory, juveniles grew poorly when competing with aggressive adults. Since emigration was not restricted in the field, however, juveniles disappeared in significantly greater numbers when the adult population was aggressive than when the adult population was docile. In addition to these experiments, the success of immigrants onto trapped out plots and plots with a resident population was examined. Immigrants were more successful in establishing themselves on trapped out plots. All the data collected support Sadleir's hypothesis, and it seems reasonable to conclude that the correlation he drew between adult aggressiveness and juvenile survival is real. However, the data collected also provide some interesting clues as to the organization of deermouse populations. An organization is proposed in which the social unit is an animal and its immediate neighbours. Within the social unit mutual antagonism is reduced. But the members of the unit maintain a high level of aggressiveness, and are intolerant of any stranger that wanders into their home ranges. The system proposed would prevent immigrants from settling, while conserving energy by reducing antagonism between familiar animals. The system would also effectively regulate population size. / Science, Faculty of / Zoology, Department of / Graduate