162 SUMMARY OF QUERENT RESEARCHES RELATING TO 



sac of adults of both sexes. They may develop till the appearance of 

 the branchial arches, when the larva emerges from the egg-envelope and 

 dies, being destroyed by the phagocytes of its host. In cases where 

 they were left alone for a month without any opening of the host, it 

 was found that development was very partial. There were traces of a 

 medullary groove, but the mesoderm showed marked de-differentiation. 

 The larvEe had developed up^to a certain point, showing adhesive organs 

 for instance, and had then gone back. J. A. T. 



Grafting Eggs of Bombinator.— A. Weber (Comptes Rendus Soc. 

 Biol, 1920, 83, 891-2). Fertilized ova of Bombinator igneus surrounded 

 by their viscous envelope were placed in the peritoneal cavity or in the 

 dorsal lymph-sac of adults of both sexes and in the peritoneum of newts. 

 The newly fertilized ovnm underwent rapid destruction, especially in the 

 newts. The development hardly got past gastrulation, but some showed 

 an irregular medullary plate. An ovum that has undergone gastrulation 

 will go on developing almost normally, but somewhat asymmetrically. 

 The stage of branchial arches was reached, and then the larva hatches 

 inside its host. J. A. T. 



Grafting Eggs of Newt. —A. Weber {Comptes Rendus Soc. Biol., 

 1920, 83, 749-51). Experiments in grafting the ova of Triton alpestris 

 in the peritoneal cavity of the adult. The ovum is covered externally 

 with a transparent and elastic membrane ; there is a delicate translucent 

 vitelline membrane in direct contact with the ovum ; between the two 

 there is a fluid corresponding to white of egg, and in this some crystals 

 appear shortly before the liatching of the larva. When the eggs are 

 placed at various stages of development in the peritoneal cavity of the 

 male they are soon killed ; the same is true in the female, but the killing 

 is rapid. The same is true of larvae enclosed for a short time in the 

 peritoneal cavity of the adult. The peritoneal reaction is slight when 

 the introduced ova are in early stages of development ; it is marked 

 in the later stages. Segmentation of introduced ova may continue for a 

 short time, but there is irregularity in the blastomeres, and the gastrula 

 stage is never passed. Introduced larvse show before they are killed 

 some de-differentiation of the organs. J. A. T. 



'^■o'- 



Pigmentation of Tadpoles. — A. Pkenant {Comptes Rendus Soc. 

 Biol., 1920, 83, 8?)9-J:2). In tadpoles of Discoglossvs p ictus a number 

 of very pale, greyish cells, at first isolated, come together and anas- 

 tomose to form a "reticulum of Asvadourova," with quadrangular 

 meshes, the whole being visible to the naked eye. Independent of the 

 reticulum there are other pigmented cells at a deeper level, and some 

 melanophores appear from connective-tissue cells. The reticulum 

 occurs in Felodytes, but nut in Pelobates, frog, or toad. It is well 

 known that tadpole and adult Batrachians have two kinds of pigment 

 cells, xanthophores with a yellowish pigment, and melanophores with 

 melanin. The xanthophores occur singly or in a reticulum (the 

 *' reseau jaune " of Mile. Asvadourova) ; they contain in many cases 

 (frog and toad tadpoles) numerous globules coloured by vital stains, 

 but these are almost always absent in tadpoles of Alytes and Disco- 



