Toad

Abstract: The relationship of the anterior pituitary to sexual maturity has been demonstrated by homoplastic implants in every major group of vertebrates. Various effects from precocious sexual maturity to induced ovulation have been reported for fishes (15); for Amphibia as represented by frogs (24, 25), toads (14, 16), Triturus (2, 20), Triton (2, 20); for reptiles as represented by snakes (15, 16); for birds by pigeons (6); and mammals by rats, mice, cats, rabbits, guinea pigs, and monkeys (6). The purpose of this paper is to summarize briefly the work on the Amphibia and to present considerable new evidence as to the quantitative factors involved and a dependable technique for induced ovulation and artificial fertilization in the frog, Rana pipiens. In general, the extract of whole sheep or cattle anterior pituitary (8) has not proven to be effective with frogs and toads, though there are possible exceptions with Rana vulgaris (3) and Discoglossus pictus (17). Both the whole sheep pituitary extract and the Antuitrin-S from pregnant human urine, as dispensed by Parke, Davis and Company, have been useful in inducing ovulation with Triturus and Ambystoma (11, 22), though the Antuitrin-S seems to be more potent. Neither of these extracts has proven useful with toads (18). Heteroplastic implants from the hen, rat, pig, dog, cattle, snake, fish, opossum and frog proved to be ineffective with respect to inducing ovulation in toads (3, 7, 15). This raised the question of "specificity," especially since the toad, Bufo vulgaris, reacts only to homoplastic implants while the toad pituitaries are effective when implanted in the frog, Rana vulgaris (3). Recent evidence (23) does not support this contentention of species specificity of pituitary, since with large doses of pituitary from the garpike, Lepidosteus, both the toad, Bufo americanus, and the frog, Rana pipiens, were induced to ovulate. It was suggested in this paper that previous failures may have been due to insufficient implantations. While heteroplastic implants between fishes and Amphibia may prove effective, no amount of pituitary from the albino rat (23) would induce ovulation in either frog or toad. Further evidence for 22

Abstract: Three types of glial cells corresponding to astrocytes, oligodendrocytes, and microgliacytes were found in the toad spinal cord stained with a modification of the Golgi-Rio Hortega technique. Each can be correlated with a characteristic type of nucleus stained with toluidine blue.

Abstract: Lateralisation of responses to presentation of a simulated predator was investigated in three species of toads: two European species (the common toad, Bufo bufo, and the green toad, Bufo viridis) and one species introduced to Australia from South America, the cane toad Bufo marinus. First a simulated snake was presented moving rapidly towards the toad in the frontal field of vision and the toad's escape responses, including jumps to the right and to the left, were recorded. No significant bias in left or right side jumping was apparent in this test. Next the simulated snake was presented in the left or right lateral field of vision in random order. Escape and defensive responses were elicited more strongly, in all three species, when the stimulus was on the toad's left side compared to its right side. Reaction times scored in the experiments with B. marinus, alone, did not differ from left to right. There were, however, species differences in the types of escape responses with respect to the laterality: B...