Gametogenesis in Cestodes. 
Von 
B. T. Toung, 
University of North Dakota. 
Mit Tafel XVII— XX. 
Abstract. 
Evidences of degeneration of mitosis in the gametogenesis of cestodes 
are given. The gern cells arise from undifferentiated (possibly in sonie 
cases from de-differentiated) somatic cells. In spermatogenesis a fairly 
typical first maturation prophase occurs, alter which the skeins break up 
and the second spermatocytes are formed from their chromidial remains. 
The process of sperm development is greatly abbreviated, and the struc- 
ture of the sperm simplified, in correlation with the rapid development of 
an enormous number. In oogenesis also maturation is started but not 
completed, no polar bodies being formed. This simplification may also 
be correlated with the development of large numbers of eggs, and the 
elaboration of yolk by the latter, the yolk gland showing evidence of 
degeneration, together with so many other organs. These observations 
have been corroborated by the study of a large amount of material, both 
living and fixed, from several different species. 
Statement of Problem. 
Interest in cestode cytology was aroused several years ago by the 
Work of Child 1904, and ’07, I— V, on Moniezia, in which he attempted to 
Show that amitosis in both somatic and germinal structures was an impor- 
tant method of nuclear increase in this worin. Since that time a number 
of workers have entered this field, and several questions have received 
considerable attention, altho the chief interest has centered in that of 
mitosis VS. amitosis. ^\Tiile it is generally admitted that mitosis is not 
as easy of demonstration in cestodes as in many other forms, and that 
certain apparent amitoses are of frequent occurrence; nevertheless many 
cases of unquestionable mitosis have been demonstrated, and the general 
