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William S Marshall and Paul H. Dernehi, 



also be inade of a view between these two in which they are formed 

 in part by each method; also of eggs like those of Campodea and 

 Platygaster in which no nuclei are present within the yolk after the 

 blastoderm is formed. Those who have held that part of the divid- 

 ing nuclei remain within the egg, that is, the nuclei do not all go 

 to the periphery to take part in blastoderm formation, are: Ayers (1), 

 Blochmann (2), Bobretzky (3), Carriere and Bürger (11), Cholod- 

 kovsky (13), Dickel (14), Graber (18) for Lina etc., Heider (23), 

 Heymons (26) for Forficida, Knower (28), Nussbaum (43), Schwartze 

 (51), Tichomiroff (52), Uzel (56) for Lepisma, Voeltzkow (58), 

 Wheeler (60) for Doryphora, and Witlaczil (62). Against this view 

 and deriving the vitellophags from the blastoderm are: Bruce (6) 

 for Meloe, Brues (7) (origin late and unknown, but no cleavage 

 nuclei remain in egg), Graber (18a) for Melolontlia, Heymons (26) 

 for Periplaneta and Grijllotalpa, Patten (44), Uzel (56) for Macro- 

 toma, Weismann (59), Wheeler (60) for Periplaneta, and Will (61). 

 It . does not necessarily follow that the authors here cited believe 

 but one way of vitellophag derivation is present among insects. 

 Contrary to this, some have worked with more than one insect and 

 found this origin different in the insects studied. As an example 

 we would call attention to Uzel's (56) paper in which the eggs of 

 Campodea are found to be without yolk nuclei, Lepisma retains part 

 of the nuclei within the center of the egg, and in Macrotoma all the 

 nuclei go to the surface, the yolk nuclei then arise from the blasto- 

 derm cells. There are also views deriving the yolk nuclei from 

 peculiar thickenings in the Keimhautblastem; also earlier ones not 

 here given. We hold that in Polistes the yolk nuclei are derived 

 from the dividing nuclei within the egg and not from the blasto- 

 derm. 



We have already called attention to the similarity of the clea- 

 vage and the yolk nuclei, holding that while resting and dividing 

 the two are similar except in their position in the egg, and also a 

 slight one in size. We have described these nuclei both resting and 

 dividing, and have nothing more to say concerning the yolk nuclei 

 previous to the stage in which the cleavage nuclei have reached the 

 Keimhautblastem. Coming to this stage we find that the nuclei 

 which remain within the egg and take no active part in blastoderm 

 formation change in their method of dividing, not in any one stage 

 or in an abrupt manner. 



In Fig. 7 we have shown an egg of Polistes in which the cleavage 



