DEMONSTRATION OF A QUANTITATIVE RELATION BETWEEN STIMULUS AND RESPONSE IN PSEUDOPREGNANCY IN THE RAT

Abstract

This paper is a critical evaluation of the results of Vogt and Haterius on the cause of pseudopregnancy in the rat. These authors abolished the pseudopregnancy due to glass rod stimulation of the cervix by removing sympathetic ganglia, thus presumably breaking the afferent path to the hypophysis. Yet, in these operated animals, copulation did produce pseudopregnancy. Haterius suggested that this was due to natural mating involving a different kind of stimulus from the artificial cervical stimulation. The author explains it as due to a stronger stimulus of the same kind since, while pseudopregnancy always occurs after copulation involving 2 or more plugs, it less frequently follows slighter stimulation, such as 1-plug mating which is shown to be about equal to glass rod stimulation. In animals in which the mechanism had been injured by cervisectomy or uterine traumatization the percentage of success after 1-plug matings was reduced although the 2-plug matings were still invariably successful. These findings point out the need for quantitative records of mating in such studies.