Germ Cells of Leptinotarsa Signaticollis. 147 



aries, which suggests that a process of liquefaction is taking place, 

 as a result of which the walls of the epithelial cells and to a less 

 extent those of the stalk cells are dissolved, producing a matrix 

 in which the nuclei of these cells are suspended. 



This diffuse effect is not a chance occurrence to be observed in 

 a few odd preparations, a result which might be attributed to an 

 artifact, but is an event that takes place regularly at what appears 

 to be a critical period in the development of the ovum. 



As this condition comes on at the time when the chromatin 

 configuration enables one to distinguish between egg cells and 

 nurse cells, it seems that there might be some causal relation 

 between the two phenomena. A study of the epithelial cells demon- 

 strates that they filter down from the upper portion of the terminal 

 chamber to its lower end, where they accumulate, and the result is 

 aninteraction between them and the contiguous cells oftheovariole 

 stalk. The semi-fluid matrix formed might then be regarded as 

 exerting a specific effect on those germ cells coming under its 

 influence, enabling them to develop into ova, while the more dis- 

 tant germ cells become nurse cells. 



For some time preceding this stage the germ cells multiply so 

 rapidly that the daughter cells do not accumulate much cytoplasm; 

 and a" section at this time shows the cells as large clear nuclei, 

 containing chromatin in the form of a spireme, around which is a 

 very narrow margin of cytoplasm (Fig. 8). These cells have com- 

 pleted their division period and therefore represent the last gen- 

 eration of ovogonia. As they enter upon the growth period they 

 move down into the diffuse region. Fig. 9 is from an adult several 

 days older, when the eggs appear with a considerable quantity of 

 cytoplasm which increases steadily in amount from now on. 

 ^ It is also to be noted that mitotic divisions continue in other 

 parts of the egg tube long after they have ceased in this region. 

 This fact tempts the suggestion that the energy which is preserved 

 in the ovocytes for the future maturation divisions and perhaps 

 the development of the embryo, is expended in mitotic divisions 

 by the nurse cells, the sister cells of the ovocytes. The occurrence 

 of tripolar spindles (Fig. 19) and abnormally large single spmdles 

 that result in the production of gigantic cells, are manifestations 



