588 
DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
d. The seniinal vesicles with an enclosed nucleus, f. The seminal vesicle 
surrounded by the granules in a very irregular manner. Magnified 330 
diameters. 
Fig. 10. Lower portion of the testicle, a. The granular or seminal masses more or 
less formed, b. The walls of the tube presenting strise as well as granules. 
Magnified 330 diameters. 
Fig. 11. Portion of the vas deferens, showing the muscular or contractile fibres that 
encircle it. Magnified 330 diameters. 
Figs. 12 
Fig. 16. 
Fig. 17. 
Fig. 18. 
Fig. 19. 
Fig. 20. 
Fig. 21. 
Fig. 22. 
Fig. 23. 
PLATE XXVI. 
— 15. Drawings representing the formation of the spermatozoon in the 
Ascaris acuminata. Copied from Wagner and Leuckardt’s article on 
‘ Semen ’ in Todd’s Cyclopaedia, a. The nucleus of the seminal cell, which 
by elongation constitutes the tail. h. The seminal cell, which is persistent 
and forms the body of the spermatozoon. 
Formation of the seminal cells, copied from Kolliker. a. The four seminal 
cells formed within, b. The mother-cell. 
Fully-formed spermatozoon of the Ascaris acuminata after Reichert, a. The 
seminal cell. b. The indefinite nucleus. c. The enlarged nucleolus. 
Magnified 300 diameters. 
Contents of the upper part of the testicle. Magnified 500 diameters, a. The 
seminal or spermatic cells, b. The granular fluid in which they float. 
d. The nucleus. 
Granular seminal masses in an imperfect state of formation, a. The irre- 
gular mass of granules, h. The enclosed spermatic cell. c. A mass sub- 
jected to pressure, by which it is resolved into a granular fluid. Magnified 
500 diameters. 
Granular masses fully formed, a. The perfect mass, presenting nothing but 
granules and quite opake. b. Masses subjected to pressure, showing the 
contained spermatic cell. c. Nucleated spermatic cells set free by pressure. 
d. A spermatic cell, which, having escaped from its granular envelope, has 
swollen up to several times its former size. Magnified 500 diameters. 
Spermatic cell seen in front, a. The transparent delicate cell-wall. b. The 
discoidal, granular and opake nucleus, c. The nucleolus. 
Spermatic cell seen in profile, a. The cell- wall. b. The granular nucleus 
now appearing lenticular, c. The nucleolus, d. The membrane covering 
the internal surface of the nucleus, apparently a portion of the cell-wall. 
Spermatic cell seen in profile. The nucleus b enlarged and having lost its 
