LiNviLLE. — Maturation Pulmooates. 



PLATE 3. 



Fig. 14. Limax agrestis. First maturation spindle, germinative vesicle having just 

 disappeared. Head and tail of spermatozoon still connected. 



Fig. 15. Limncea sp.? First polar cell remains. Second polar cell formed, but broken 

 away from the egg ; its " Zwischenkorper " remains near that of the 

 first polar cell. Sperm-head just broken off from the tail, and with base 

 turned toward the egg-nucleus. The sperm-head lies in a vacuole. Two 

 centrosoraes (?) may be seen each in a bundle of rays in the vacuole on 

 the side away from the proximal end of the tail. 



Fig. 16. Limax maximus. Formation of the first polar cell. Centrosphere with thick 

 reticulated wall ; no centrosome is visible. Clear area of centrosphere 

 finely reticulated. Sperm-head in lower part of figure. 



Fig. 17. Limax maximus. First polar cell just formed. Vacuolation or enlarging 

 of centrosphere begun. Two centrosomes (?) in the centrosphere. 

 Sperm-head in usual vacuole. Sixteen dyads in first polar cell. 



Fig. 18. Limax maximus. Centrosomes about to form the first cleavage spindle. 



Fig. 19. Limax agrestis. Polar cells lost. First cleavage spindle forming. 



Fig. 20. Limax maximus. First polar cell lost ; second polar cell still united to the 

 egg. The germ-nuclei are nearly surrounded by numerous small bodies 

 resembling centrospheres. 



Fig. 21. Limax maximus. First polar cell just formed. Enlargement of centro- 

 sphere further advanced than in Figure 17. Two minute centrosomes 

 with radiations within the centrosphere. Sperm-head with problematic 

 centrosome within the sperm vacuole Blunt end of tail is the one to 

 which the sperm-head was attached. 



Fig. 22. Limax maximus. Telophase of first cleavage spindle. Nuclear membrane 

 already formed about the chromosomes. Centrosomes divided in anti- 

 cipation of the next cleavage. 



