If a causative virus can be demonstrated in mesenchymatous fowl tumors, either in those originating spontaneously4 or induced by chemical carcinogens,3 and if at least two other viruses are the probable causes of two epithelial tumors, one in the frog (R. pipsens)2 and the other in the Triton (7. alpestris),' it would obviously be interesting to ascertain whether viruses could be demonstrated i...

Rhabdias kongmongthaensis sp. n. is described based on specimens found in the lungs of the tree frog Polypedates leucomystax (Gravenhorst) (Amphibia: Rhacophoridae) from Kanchanaburi Province, western Thailand. The new species is similar to two North-American species, Rhabdias ranae and R. americanus, by presence of two lateral pseudolabia, each with two inner submedian protuberances. R. kongmo...

Two-cell mouse embryos were cultured in vitro for different periods in a medium in which NaCl was partially replaced by LiCl at concentrations ranging from 1 to 30 mM. The relative cell number diminished according to increasing LiCl concentrations but the onset of blastulation was not affected, thus resulting in blastulae with fewer cells than normal and with a reduced or absent inner cell mass...

Among adult vertebrates, only some of the amphibia are capable of regenerating their limbs. Several years ago experiments were begun in an attempt to induce neoplasia in limb tissues capable of such regeneration. The common newt, Triturus viridescens, was used because of its hardiness and availability. The injection of a variety of supposedly carcinogenic substances into the forelimb of over 50...

O N the basis of earlier experimental results on amphibia and his own observations, Yntema (1955) came to the conclusion that the 'ear rudiment or the ectoderm surrounding it may be a source of mesectoderm for the ear capsule, at least in the heterotopic position'. This is contrary to another view that the source of the cartilaginous ear capsule is of purely mesentodermal origin. The literature...