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All discussions based upon the behavior of isolated blastomeres have hitherto been hampered by the complete lack of data regarding the highly differentiated and mosaic-like types of cleavage such as occur among gasteropods and annelids. The present paper, which deals with the development of isolated blastomeres of the gasteropod IZyanassa obsoleta, STIMPSON(More)
The following paper embodies, in the main, the results of a further study of some modifications of fertilization and cleavage in sea-urchin eggs along" the lines first marked out by O. and R. I-IERTWIG ('87) in their classical paper l~ber den B e f r n e h t u n g s und T h e i l u n g s v o r g a n g des t h i e r i s e h e n Eies u n t e r dem E in f lu s(More)
1. The unfertilized eggs ofChatopterus, taken near the beginning of the maturation-period, may readily, by strong centrifuging, be broken into fragments of varying size and contents. Both nucleated and non-nucleated fragments of various sizes may be fertilized, and may develop into actively swimming dwarf larvae, some of which approach the normal whole(More)