ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 379 



overgrowth, but all died except two before the hind limbs broke through. 

 Oue of the survivors died at the critical time when the germ-cells were 

 Iteginning to be differentiated, but would apparently have been a male. 

 The other grew to two and a half times the normal size, but just as the 

 front limbs had appeared it jumped out of the water and died. When 

 the gonads were sectioned, the tadpole was found to be a well-developed 

 male. * 



Morphogenesis of Monsters.* — E. I. Werber has experimented with 

 the eggs of Fundulus heferoclitus, subjecting them to the action of some 

 substances which occur in metabolic toxemia. Positive results were 

 got particularly from butyric acid and acetone, which are produced in 

 disturbances of carbohydrate metabolism. A great variety of monsters 

 resulted, affecting the eyes (cyclopia, synophthalmia, monophthalmia 

 asymmetrica, and'anophthalmia), the ear vesicles (rudimentary develop- 

 ment, presence of only one vesicle, synotia), the olfactory pits, the 

 mouth, the central nervous system, the heart and blood-vessels, the fins, 

 and the body form. CEdematous conditions w^ere found in many 

 embryos lacking a continuous system of blood circulation in various 

 parts. 



The chemically changed environment brings on blastolysis which 

 destroys or disperses the germinal substance. The blastolysis may be 

 chemical, altering (by solvent or precipitating or coagulating action) 

 the germ's substance. This alteration results in dissociation or disinte- 

 gration of parts of the substance (defect), or, occasionally, in a decrease 

 m the germ's chemical capacity for development and differentiation 

 (inhibition). 



The blastolysis may also be osmotic, increasing the permeability and 

 allowing sea-water to enter the eggs. The inhibition of se.x-water by 

 the eggs, which swell rapidly, calls forth a fragmentation of the germ^ 

 and dispersion of parts which are still capable of further independent 

 development and differentiation. 



Almost all eye terata are due, not to inhibition, but to a defect, viz. 

 to blastolytic elimination of a fragment of either ophthalmoblastic or 

 potential inter-ocular material. Only such cases of anophthalmia, 

 where on microscopic examination rudiments (ill-differentiated optic 

 vesicles or cups) are found, form an exception to this rule. Here an 

 inhibition is assumed, due to a decrease of the chemical capacity for 

 development (chemical exhaustion). 



The frequent occurrence of ophthalmic and anterior terata is ascribed 

 to a higher degree of susceptibihty in the earliest embryonic primordium, 

 which eventually becomes the embryo's anterior end (animal pole). 

 This is suggested by Child's discovery of a definite susceptibility 

 gradient. 



The numerous meroplasts recorded, especially such teratomata as the 

 " solitary eye " and the " isolated eye," point to a very high degree of 

 capability of parts of the embryonic primordium for independent 

 development and differentiation (the " self-differentiation " of Eoux). 



* Journ. Exper. Zool., xxi. (1916) pp. 485-582 (3 pis.). 



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