Linvillb. — Maturation Pulmonates. 



PLATE 4. 



All Figures, except Figure 25, are of eggs of Limncea elodes. 



Fig. 23. First maturation spindle. At either pole of the spindle is collected a mass 



of precipitate, the whole resembling a so-called centrosphere. 

 Fig. 24. First maturation spindle. Apparently the centrospheres were in the process 



of being decolorized when the process of decolorizing was checked. 

 Fig. 25. Limax agrestis. The germinative vesicle contains two nucleoli and 



" Linin " fibres with elements of future chromosomes arranged in 



" skein " stage. 

 Fig. 26. First cleavage spindle. Structures that seem to be the sperm-chromosomes 



now occupy the middle of the spindle, and the egg-chromosomes are 



about to be drawn into it. 

 Fig. 27. First cleavage spindle. Rays near the incipient spindle are beginning to 



penetrate the sperm nucleus, while the egg-nucleus is still unaffected. 



The chromosomes are not yet formed. 

 Fig. 28. First cleavage spindle. The sperm-chromosomes occupy the whole breadth 



of the spindle, while the egg-chromosomes are at one side of the spindle. 



The granular funnel beneath the polar cells probably represents the path 



through which the egg-chromosomes were drawn to the spindle. 



