70 Edmund B. PFilson. 



ences in the period of segregation (or differentiation) and in its 

 pattern, and are explicable under the general theory of precocious 

 segregation. 



12. The early development of egg-fragments indicates that 

 the specification of the cytoplasmic regions is primarily qualitative, 

 but not quantitative, or if quantitative is still subject to a regulative 

 process that lies behind the original topographical grouping of 

 the egg-materials. 



13. The development of the molluscan egg is in its essential 

 features a mosaic-work and sustains the theory of "Organbiln 

 dende Keimbezirke." 



LITERATURE. 



BovERi, Th., '92. — Befruchtung : Merkel u. Bonnet, Ergebn. I. '9i-'92. 



'97. — Zur Physiologic der Kern- und Zelltheilung: Sitzungsber. d. 



phys.-med. Ges. Wiirzburg. 

 '01, I. — tjber die Polaritat des Seeigeleies : Verb, phys.-med. Ges. Wiirz- 

 burg. (N. F.) XXXIV. 

 '01, 2. — Die Polaritat von Ovocyte, Ei und Larve des Strongylocen- 



trotus lividus: Zool. Jahrb. (Anat.-Ontog.) XIV, 4. 

 '02. — tJber mehrpolige Mitosen. Verb, phys-med. Ges. Wiirzburg. (N. 



F.) XXXV. 

 '03. — liber den Einfluss der Samenzelle auf die Larvencharaktere der 

 Echiniden : Arch. Entwm., XVI, 2. 

 Child ,C. M., '02. — Fission and Regulation in Stenostoma : Arch. Entwm.,X V,2. 

 CoNKLiN, E. G., '99. — Protoplasmic Movements as a Factor in Differentiation : 

 Wood's Hole Biol. Lectures. 1898. 

 '02. — Karyokinesis and Cytokinesis in the Maturation, Fertilization and 

 Cleavage of Crepidula and other Gasteropoda : Journ. Acad. Nat. 

 Sci., Phila. II. Ser. XII, i. 

 Crampton, H. E., '96. — Experimental Studies on Gasreropod Development ; Arch. 

 Entwm. III. 



'97-— The Ascidian Half-Embryo : Ann. N. Y. Acad. Sci., X. • 

 Delage, Yves, '99. — fitudes sur la merogonie : Arch. Exp, Zool. (Ser. III.), VII. 

 '01. — fitudes experimentale sur la Maturation cytoplasmique chez les 

 Echinodermes: Arch. Exp. Zool. (Ser. Ill) IX. 

 Driesch, H., '92. — Entwickelungsmechanisches : Anat. Anz., VII, 18. 



'96. — Betrachtungen iiber die Organisation des Eies und ihre Genese : 



Arch. Entwm. IV. 

 '98. — tlber rein -miitterliche Charaktere an Bastardlarven von Echiniden : 



Arch. Entwm., VII. 

 '99. — Resultate und Probleme der Entwickelungsphysiologie der Thiere : 



Merkel u. Bonnet, Ergebn. VIII. 

 '00. — Die isolirten Blastomeren des Echinidenkeimes : Arch. Entwm. X, 



