310 H. H. NEWMAN. 



theses with fish embryos. He consequently subjected the 

 embryo of the fish Fundulus to solutions of various metabolic 

 by-products, characteristic of normal and pathologic mammals, 

 such as urea, butyric acid, lactic acid, acetone, sodium glyco- 

 cholate, and ammonium hydroxide. Conclusive results were 

 obtained only with butyric acid and acetone, especially the 

 latter. The paper is especially valuable for its comprehensive 

 record of terata, their classification, and the numerous figures of 

 monsters of every sort. All of the results are similar to those 

 obtained in hybridization experiments, as is evidenced by the 

 fact that the illustrations would serve as well for a paper on 

 hybrid teratomata as for the paper in which they appear. All 

 of Stockard's teratomata are also duplicated exactly. 



It is especially to be noted that there are two markedly different 

 types of monsters: (a) those in which the head parts alone are 

 inhibited, and especially the eyes and heart, and (&) those in 

 which the head parts develop fairly normally and the posterior 

 parts are inhibited. Extremes of (a) are seen when only the 

 eyes or heart are effected, and of (&) when eyes or heart develop 

 alone to the exclusion of other parts of the body. These results 

 appear at first sight quite paradoxical, but the explanation will 

 be clear from what follows. 



Werber appears to realize the importance of Child's theory 

 of the "axial gradient" in organisms as an aid in understanding 

 the morphogenesis of monsters. He points out that the anterior 

 end, or "apical end" is most susceptible to agents that inhibit 

 development, and hence we have a logical basis for the frequency 

 of ophthalmic terata. He sees in Child's work however no ex- 

 planation of the occurrence of heads with reduced body and of 

 isolated eyes, hearts, etc. 



Werber's idea of the morphogenesis of monsters differs some- 

 what from that of Stockard in being strongly morphological. 

 According to him any chemical substance, whether anaesthetic, 

 toxic, or what not, so long as it is injurious to life, checks the 

 process of cell metabolism and cell division and causes the affected 

 cells to disintegrate. This "differential blastolysis" accounts to 

 Werber's mind for the suppression of certain anlages, especially 

 of those at the apical end of the embryo ; but it fails to account 



