ABNORMALITIES IN CESTODE MONIEZIA. 159 



opment of those regions of the proglottid in which they lie. 

 Reduction of any given region means reduction in amount of 

 material and in space, and the organs which develop in this 

 region must be affected. The organs of the normal proglottid 

 are the only organs possible under the given conditions of form, 

 size, etc. Change in the conditions must produce alterations in 

 the organs. The correlation between form and structure as 



o 



shown in the variations is so close that, given a proglottid of a 

 certain form, it would be possible to predict with a considerable 

 degree of accuracy in most cases what the condition and general' 

 arrangement of the organs would be. It is scarcely necessary 

 to seek for a common cause for this correlation of form and struc- 

 ture. I think it is sufficiently clear that the variations in form of 

 the proglottids are the cause of the variations in structure and 

 arrangement of the proglottidal organs. 



HULL ZOOLOGICAL LABORATORY, 



UNIVERSITY OF CHICAGO, March, 1901. 



LITERATURE. 



In the references to literature I have followed the plan pro- 

 posed recently by Bather ('oi), viz., the use of the last two nu- 

 merals denoting the year for all papers which have appeared 

 within the hundred years preceding the paper. 



Bather, F. A. 



'oo A Bibliographic Catch Title for Ever and Ever. Science, N. S., Vol. XIII., 

 No. 319. 



Child, C. M. 



'oo Abnormalities in the Cestode Moniezia expansa. Biol. Bull., Vol. I., Nos. 

 5 and 6. 



Cohn, L. 



'98 Untersuchungen iiber das Centrale Nervensystem der Cestoden. Zool. Jahrb. : 

 Abth. f. Anat. and Ont., Bd. XII., H. I. 



Koehler, E. 



'94 Der Klappenapparat in den Exkretionsgefassen der Tanien. Zeitschr. f. 

 wiss. Zool., "Bd. LVII. 



Lu'he, M. 



'96 Das Nervensystem der Ligula in seinen Beziehungen zur Musculaten. Zool. 

 Anz., Bd. XIX. 



