572 
DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
the oviduct (fig. 90 c, c?) contains a transparent, finely-granular fluid with only an 
ovule here and there. It is therefore probable that a peristaltic action being set up 
by the transverse muscular fibres of the oviduct, the ovules are detached and forced 
forwards singly into the uterus (fig. 90 f). Another constriction (fig. 90 d), but not so 
well marked as the first (fig. 90 c), indicates the termination of the oviduct, beyond 
which the tube becomes suddenly dilated into the uterus (fig. 90 /), which is several 
times the diameter of the preceding portions. 
The uterus commences by a rounded extremity or fundus (fig. 90 f), into which 
the oviduct (fig. 90 c, c?) opens, and gradually becomes narrower until it unites with 
its fellow (fig. 92 f) to form one tapering vagina (fig. 92 g). The uteri are formed of 
an external membrane (Plate XXVII. fig. 4^ h) lined with broad, flat, quadrangular 
cells (fig. 43 r), each of which presents an oval or round nucleus (fig. 43 s) and a 
central nucleolus (fig. 43 t), of great beauty and distinctness. 
Lastly, the vagina presents some transverse muscular rugse externally, with nu- 
cleated flat cells internally, completing thus the complex structure of the female 
reproductive apparatus. 
The csecal extremity of the ovary (fig. 39 a) throws off, as I have said, small rounded 
granules (fig. 39 c), which enlarge rapidly and form the germinal vesicles (fig. 39rf). 
These granules are formed by the thickened apex, and give its substance a semi- 
transparent structure (fig. 39tt). A fluid likewise fills the upper part of the ovarian 
tube, of an albuminous nature, and apparently the secretion of its walls. The ger- 
minal particles or granules when first thrown off, by the internal surface of the caecal 
apex, are only i^th of an inch in size (fig. 39 c), but begin almost immediately to 
increase to several times their original bulk, become vesicular (fig. 39 d), and present 
a nucleus within each cell (fig. 39/'). These are the germinal vesicles, and their in- 
cluded nuclei are the germinal spots (fig. 39 d,f). 
Kolliker describes the invaginated appearance of the upper end of the ovary 
(fig. 39 b) as large cells whose nuclei are the germinal spots, which are set free by 
the successive openings of these large cells. (See Muller’s Archiv for 1843.) 
He further states that the germinal spot is first formed, and around it the germinal 
vesicle is developed like a primitive cell round its nucleus. My observations, how- 
ever, lead me to believe that a germinal particle is first formed (fig. 39 c), which ap- 
pears semiopake and solid (fig. 44-1-); and that by the imbibition of the surrounding 
fluid the external membrane or layer of this germinal particle is distended, and thus 
forms the germinal vesicle (fig. 44 b), leaving the solid contents to form a central 
nucleus or germinal spot (fig. 44 a). 
The germinal vesicles (fig. 39 d) are now of an inch in size ; as they pass 
down the ovary they disappear (fig. 40 A), becoming enveloped by opake granules 
(fig. 39 g). 
At first, that is to say in the upper part of the ovarian tubes, these granules (fig.39g) 
are perfectly free, floating loosely in the fluid that surrounds them and lying in con- 
