9O H. J. VAN CLEAVE. 



Since the past history of the specimens under consideration has 

 not been available data concerning the age of individuals and 

 source of the strains are not directly obtainable. Consequently 

 the conditions operating to produce the abnormal glands are not 

 known. In addition to the three instances of abnormal numbers 

 of nuclei in the vitellarium mentioned above, numerous other va- 

 riations from the usual structure have been observed. Frequently 

 the nuclei are heavily vacuolated (Figs. 3, 4, 5 and 8). An ex- 

 treme example of vacuolization is shown in Fig. 3 in which one 

 nucleus has attained such a high degree of vacuolization that its 

 chromatic material is highly dispersed and the nucleus greatly 

 swollen. 



i 



A more common type of abnormality, possibly associated with 

 advanced age and apparently of significance in considering the 

 problem of increased numbers of nuclei, is that of change in form 

 of the nuclei. Development o>f irregularity of outline and elonga- 

 tion with accompanying constrictions are two of the more com- 

 mon types of such anomalies. Figs. 4, 5, 6 and 7 show character- 

 istically constricted, lobed, angular, indented, and twisted nuclei. 

 These varying forms all give the appearance of adaptations de- 

 scribed in the literature on cytology for increase in nuclear sur- 

 face necessitated by some change in the normal activity of the 

 gland. In this specific instance no experiments have been per- 

 formed to determine the conditions responsible for this attempt at 

 readjustment of nuclear surface to meet increased demands. It 

 does seem significant that the changes in form of the nuclei 

 closely resemble conditions observed in other tissues the nuclei of 

 which are undergoing amitotic fragmentation. From nuclei such 

 as shown in Figs. 4 and 6 it is no very great step to a separation 

 of the constricted parts into independent nuclear masses. 



Modifications of an identical type have been observed in diffe- 

 rent genera of Acanthocephala. As shown by the writer (Van 

 Cleave 1914) members of the family Neoechinorhynchidse display 

 six giant nuclei in the entire subcuticula. In all genera of this 

 family these subcuticular nuclei are definitely limited ovoid or 

 elliptical masses. In members of the genus Quadrigyrus (Van 

 Cleave 1920) these same subcuticular nuclei are of two types, 



