NO. 3 EMBRYOLOGY OF FLEAS KESSEL 69 



Wheeler, W. M. 



1889. The embryology of Blatta germanica and Doryphora decemlineata. 

 Journ. Morph., vol. 3, pp. 291-372. 



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pp. 216-220, 233-236, 253-258. 



1893. A contribution to insect embryology. Journ. Morph., vol. 8, pp. 1-160. 

 Wiesmann, R. 



1926. Zur Kenntnis der Anatomie und Entwicklungsgeschichte der Stab- 

 heurschrecke Carausius morosus. III. Entwicklung und Organo- 

 genese der Colomblasen. Zool. Vergl. Anat. Inst. Univ. Zurich, 

 pp. 1-205. 



WlGGLESWORTH, V. B. 



1934. Insect physiology. Pp. 1-134. London. 

 Will, L. 



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 Anat. Ontog. Thiere, vol. 3, pp. 201-286. 

 VVray, D. L. 



! 937- The embryology of Calendra callosa Olivier, the southern corn 

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 vol. 30, pp. 361-409. 



EXPLANATION OF PLATES 

 Plate i 



Fig. 1. The micropylar apparatus at the posterior pole of an egg of Nosopsyllus 

 fasciatus showing a tendency toward a spiral arrangement of the 

 openings. X 200. 



Fig. 2. Longitudinal section through a portion of the chorion at one end of an 

 egg of Hystrichopsylla dippiei showing the volcanolike raised pro- 

 cesses and the thick rigid shell of this species. X 250. 



Fig. 3. Transverse section through a Ctenocephalides felis egg in the third 

 blastema substage. Enlargements of this section are shown in 

 figures 10 and 11. X 100. 



Fig. 4. Margin of a section of a Ctenocephalides felis egg in the first blastema 

 substage showing the vitelline spheres with their contained re- 

 fringent vitelline bodies. Two nuclei may be seen in the periplasm. 

 X450. 



Fig. 5. Margin of a section of a Ctenocephalides felis egg in the second blastema 

 substage. This is an enlargement of a portion of the section shown 

 in figure 40. X 450. 



Fig. 6. Posterior margin of a section of a Ctenocephalides felis egg in the 

 second blastula substage showing the transition from the thinned 

 dorsal blastoderm to the thicker ventral blastoderm. A sagittal 

 section through an entire egg at this stage is shown in figure 50. 

 X450. 



Fig. 7. Longitudinal section through a Ctenocephalides felis egg in the first 

 blastula substage. X 100. 



Fig. 8. Anterior margin of a section of a Ctenocephalides felis egg in the 

 fourth blastema substage showing the nuclei crowded together in 

 the periplasm. X 450. 



