摘要：

This chapter discusses the cytology of coccids. The evolution of cytological mechanisms within the group and the bearing of the data on coccid systematic are briefly discussed. Only nuclear or chromosomal cytology is considered. The data of coccid cytology discussed is in reference to the analysis of the diverse mechanisms evolved in various groups. Their bearing on general cytological problems other than mitosis and sex determination has been only incidentally indicated. In structure and behavior, the salient features of the coccid chromosome stem directly from the diffuse nature of the kinetochore. The kinetic functions are a property of the chromosome as a whole and are not, as in most organisms, restricted to a specialized zone or organelle. Structurally this is evident in the absence of tall stages of the chromosome cycle of any primary constriction or localized kinetochore. In mitosis, the diffuse kinetochore results in distinctive types of orientation at metaphase, mode of formation of chromosomal fibers, and anaphase disjunction, and the potentiality realized to varying degrees in different tissues and species of complete spatial separation of the constituent chromonematal strands of the chromosome.

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