1 62 A. RICHARDS. 



evident in my preparations; and finally, (3) that there cannot 

 be the slightest doubt that the cleavage of the ovum takes place 

 by mitosis. 



NOTE. 



While this paper was in press an article by Gough ["A Monograph of the Tape- 

 worm of the Subfamily Avitellininae, being a revision of the Genus Stilesia, and 

 an account of the Histology of A vitelli na centri punctala (Riv.)"] appeared in the 

 Quarterly Journal of Microscopical Science for February, 1911, wherein he describes 

 the development of the eggs of Avitellina. He, too, finds Zenker's fluid best for 

 cestodes. As in Moniezia, yolk cells do not become attached to the eggs to form 

 compound structures. The large mass which he calls chromatin (Figs. 57-63) 

 apparently correspond to my nucleoli (my Fig. 30) ; there can be no doubt that in 

 Moniezia these are nucleoli and that no other nucleolar structures occur, as shown 

 by differential staining. The extrusion into the cytoplasm of chromatin which 

 breaks up to form the yolk nucleus (see p. 373) has not been observed in Moniezia. 

 I would suggest that his Fig. 63 perhaps corresponds to my Fig. 26 which is a 

 synapsis stage not merely the first step in a mitosis. Gough speaks of the 

 maturation mitoses as occurring very rapidly. As Stilesia, and, therefore, 

 Avitellina is quite closely related to Moniezia the comparison of the two is of 

 interest, particularly with regard to the fact that compound eggs do not occur 

 in either 



LITERATURE REFERENCES. 

 Balss, H. H. 



'08 Ueber die Entwicklung der Geschlectsgange bei Cestoden nebst Bemerkung 



zur Ectodermfrage. Zeitschr. f. wiss. Zool., Bd. 91. 

 Boveri, Th. 



'07 Zellenstudien, 6, p. 235. G. Fischer, Jena. 

 Bugge, G. 



'02 Zur Kenntnis des Excretionsgefass-Systems der Cestoden und Trematoden. 



Zool. Jahrb., Vol. 16, Anat., s. 177. 

 Gary, L. R. 



'09 The Life History of Diplodiscus temporatus Stafford. Zool. Jahrb. (Anat. 



und Ont.), Bd. 28. 

 Child, C. M. 



'04 Amitosis in Moniezia. Anat. Anz., Bd. 25. 



'06 The Development of Germ Cells from Differentiated Somatic Cells in 



Moniezia. Anat. Anz., Bd. 29. 

 '070 Amitosis as a Factor in Normal and Regulatory Growth. Anat. Anz., 



Bd. 30. 

 '07 Studies on the Relation between Amitosis and Mitosis. In Biol. Bull., 



Vols. 12 and 13. 

 '076 I. Development of the Ovaries and Oogenesis in Moniezia. 



II. Development of the Testes and Spermatogenesis in Moniezia. 



III. Maturation, Fertilization, and Cleavage in Moniezia. 



IV. Nuclear Divisions and Somatic Structures in the Proglottids of 

 Moniezia. 



'10 The Occurrence of Amitosis in Moniezia. Biol. Bull., XVIII. 



