MICHIGAN ACADEMY OF SCIENCE. 125 



It may be said in conclusion that the eggs of insects, although supposed 

 by many embryologists to be the most highly organized of any animal eggs, 

 may have their contents profoundly distur])ed without preventing the 

 ])roduction of a normal eml)ryo. The cytoplasm and the nuclei of centri- 

 fuged eggs are forced out of their usinil positions but often nornud develop- 

 ment takes place. This would indicate that a high degree of organization 

 <loes not prevent the egg from adapting itself to changed conditions. 



The University of. Michigan, April 1, 1909. 



LITERATURE LIST. 



Born, 1885. Uel^er den Einfluss der Schwere auf das Froschei. Arch. f. 

 inikr. Anai. Bd. 24. 



Conklin, E. G., 1908. The Mechanism of Heredity. Science X. S. \'ol. 27. 



Gurwitsch, A., 1904. Zerstdrbarkeit und Restitutionsfahigkeit des Proto- 

 }:)lasmas des Amphibieneies. Anat. Atiz. Ergctnzungsheft z. Bd. 25. 



Hegner, li, W., 1908. Observations on the Breeding Hal)its of three 

 Chrysomelid Beeltes, Calligrapha bigsl)yana, C. multipunctata and C. lunata. 

 Psyche. Vol. 15. 



Hertwig, O., 1897. Ueber einige am befruchteten Froschei durch Centrif- 

 ugalkraft hervorgerufene Mechanomorphosen. Sitz. Ber. Akad. Wiss. 

 Berhn, 1897. 



Lillie, F. R., 1906. Observations and Experiments concerning the Elemen- 

 tary Phenomena of Emln-yonic Development in Chaetoperus. Journ. 

 Exp. Zoot. Vol. 3. 



Lillie, F. R., 1909. Polarity and Bilaterality of the Annehd Egg. Ex- 

 periments with Centrifugal Force. Biol. Bull. Vol. 16. 



Lyon, E. P., 1907. Results of Centrifugahzing Eggs. Arch. Ent. Mech. 

 Bd."^23. 



Morgan, T. H., 1902. The Relation between Normal and Abnormal 

 Development of the Embryo of the Frog, as Determined ])y Injury to the 

 Yolk Portion of the Egg. Arcg. ErU. Mech. Bd. 15. 



Roux, W., 1884. Beitrage zur Entwicklungsniechanik des Embryo. 

 Breslaur Arzil. Zeitschr. 1884. 



Whitney, D. D., 1909. The effect of a Centrifugal Force upon the Develop- 

 ment and Sex of Parthenogenetic eggs of Hydatina Senta. Journ. E.Tp. 

 Zool. Vol. 6. 



Ann Arl)()r. April 1. 1909. 



