ORIGIN OF MONSTERS • 551 



on transfer to sea-water. The degree of resistance to the latter 

 is the lowest at the point where the chemical alteration has been 

 the greatest. Owing to this circumstance, apparently, it is from 

 this part of the germ's substance that small fragments become 

 occasionally split off by the pressure and shifted away from the 

 potential embryo's position on the yolk. The increased osmotic 

 pressure probably destroys entirely some eggs, for shortly after 

 transfer of the surviving eggs to pure sea-water a number of them 

 can usually be found to be dead. In some instances, however, 

 small parts of such an egg which suffered great destruction from 

 osmotic pressure may survive. This fragment, occasionally, 

 by its differentiation into a solitary eye betrays its origin from 

 the anterior portion of thfe potential medullary plate. 



In commenting on the case which he reports, Loeb (I.e.) 

 remarks that ''the analogy with teratomata is obvious." Re- 

 garding this point I fully agree with Loeb, although teratomata 

 could not by any means owe their origin to degeneration of an 

 already formed embryo. They develop from fragments of the 

 embryonic primordium which has sustained (blastolytic) injuries 

 before the differentiation of tissues and organs. This point I 

 have very recently ascertained by observation on living eggs, 

 and I can fully confirm the correctness of Roux's ('95) generali- 

 zations on the subject. The latter author discussing the signifi- 

 cance of some monsters recorded in the teratological literatm'e 

 arrives at the following conclusions (p. 205) : 



Die Ursachen dieser hochgradigen Defect-und auch zum Theil der 

 grossen Deformationsmissbildungen wirken, so viel wir jetzt sehen, 

 schon zu Zeiten, ehe die einzelnen Organe und Gewebe vollkommen 

 angelegt oder ausgebildet sind; daraus folgt, dass die hetreffenden Theile 

 des Embryo 'nach' so hochgradigen Storungen ihrer selbsf oder ihrer 

 Nachbarschaft nicht bios noch am Leben zu bleiben, sodern sogar in 

 einer oft noch an das Normale erimiernden Weise sich formal und geweb- 

 lich zu differenzireji vermogen. 



And further on, commenting on the capacity of small parts 

 of an embryo to develop and to differentiate, Roux thus says 

 (p. 207): 



Wir ersehen aus den angefiihrten Beispielen, dass viele 'Theile' des 

 Embryo unter giinstigen Erndhrungsumstdnden sich unabbangig von ihrer 



