1893.] NATURAL SCIENCES OF PHILADELPHIA. 75 



THE INHERITANCE OF MODIFICATIONS DUE TO DISTURBANCES OF 



THE EARLY STAGES OF DEVELOPMENT, ESPECIALLY IN THE 



JAPANESE DOMESTICATED RACES OF GOLD-CARP. 



BY JOHN A. RYDER. 



The recent experiments in shaking apart the cells produced by 

 the first cleavage in the eggs of Echinoderms by Driesch, and of 

 Amphioxus by Wilson, as well as the experiments of Roux, in the 

 same direction, with frogs' eggs, show that it is possible for a single 

 oue of the two blastomeres resulting from the first segmentation to 

 produce at once a complete embryo, or at any rate to finally recon- 

 stitute the missing half by means of what Roux has called post- 

 generation as in the case of the frogs' eggs. 



These experiments, leading to the development of two separate 

 embryos from the same single egg, have been regarded as so remark- 

 able that they have caused a good deal of discussion. They are, 

 however, it seems to me, to be regarded as having much in common 

 with phenomena that at first thought seem to be widely distinct 

 from them, namely, the production of monstrosities in invertebrates 

 and vertebrates. The occasional duplication of peripheral parts 

 also, such as the tail in lizards when broken off, and an excess of 

 toes or fin-rays, perhaps, may be regarded as belonging ulti- 

 mately to the same category of phenomena, with a similar sec of 

 causes operating to produce them, namely, profound disturbances of 

 the normal processes of karyokinesis during development or at the 

 moment of the beginning of the regeneration of lost parts. 



Weber's experiment, reported many years ago, proving that the 

 eggs of the common pike, Esox ludus, could be caused to produce 

 double monstrosities if the recently fertilized ova were violently 

 shaken, is well known. The experience of fish-culturists in hand- 

 ling the eggs of Salmonoids is also well known. A man of very 

 great experience in the fish-cultural establishments of Austro- 

 Hungary informed me some years since that so great was the danger 

 in roughly handling or shaking the ova of the Salmonoids, during 

 the very early stages of their development, that carelessness in this 

 respect would result in producing monstrosities almost exclusively. 

 I have myself, while employed as an assistant by the U. S. Fish Com- 

 mission, seen batches of salmon brood, which were almost entirely 

 composed of fry that had developed as double or triple monsters, 

 -each with but a single yolk. 



