J. F. McCLENDON. 



In Lcemargus the egg strings are packed in loops 



under broad lamellar coverings. 



IV. OOGENESIS AND MATURATION. 



i . Oogenesis. 



A. The Dichelestid. - -The oogonia (Fig. i) are 

 very small isodiametrical cells. The nucleus is 

 spherical and contains chromatin granules in a 

 peripheral linin reticulum. Minute nucleoli are also 

 embedded in this reticulum. The cytoplasm stains 

 deeply. I have found but few oogonial mitoses in 

 this species although I have sectioned over a hun- 

 dred females ; the number of chromosomes is the 

 same as in the primary germ cells of the embryo 

 (16) and tivice the reduced number (8). 



The primary oocyte is readily distinguished from 

 the oogonium by its nucleus being about half the 

 size of the latter (when first formed). The earliest 

 stage I have is the late telophase, in which the 

 chromosomes are drawn together as though at the 

 pole of the spindle, yet the whole mass is surrounded 

 by a nuclear membrane (Fig. 2). The nuclear 

 membrane is therefore formed of the fused linin 

 sheaths of the chromosomes (or from cytoplasm ?). 

 This mass is placed excentrically in the nucleus 

 and the individual chromosomes are so pressed 

 together or fused that only their ends sticking out 

 can be distinguished separately, so that it resembles 

 a " synapsis." The cytoplasm stains deeply. The 

 oocytes are arranged in single linear series as stated 

 above and are pressed and flattened one against the 

 other ; the nuclei are close to the free surfaces of 

 the cells, and that edge of an oocyte containing the 

 nucleus is thicker than the opposite edge. Soon 

 the chromosomes swell and the chromatin becomes 



FIG. 3. The Dichelestid, ventral view of J . The ovaries and ovi- 

 ducts are solid black. Portions of the egg strings are still attached. 



