DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
577 
already said that the spermatic particles become first applied to the periphery of the 
ovule (Plate XXVIII. fig-. 60 g); and that a little later they are seen to indent the 
surface. 
Still lower we find the spermatic particles imbedded in the substance of the ovule 
to a greater or less degree, and surrounded by the vitelline granules that have been 
displaced (fig. 58 g). Sometimes only one is seen to be thus imbedded (fig. 58g), but 
more commonly several spermatic particles are applied at the same place, with their 
closed ends directed in general towards the centre (figs. 59, 60 gg). Penetration 
then takes place, the particles passing into the substance of the ovule, amongst the 
vitelline granules, and surrounded by the clear substance (figs. 59, 60 A). 
I have seen the spermatic particles in all stages of penetration, from mere contact 
(fig. 60 g) to perfect involvement within the ovule (figs. 59, 60 h). In their course they 
appear to create very little displacement, passing readily in all directions amongst 
the granules ; their transparency and high refractive power rendering them easily 
distinguishable when near the surface (figs. 59, 60 h). 
Of the possibility of penetration, no one who has ever seen an ovule of this Ascaris 
can have the slightest doubt, composed as it is of a clear gelatinous substance, 
without an enveloping membrane; while the very granules it encloses (fig. 51 c), 
there is great reason to believe, have at some period entered from without. 
With regard to the probability, there is the breaking up of the surface of the 
ovule in certain places (figs. 58 to 60 c), rendering it still easier for the entrance of 
the spermatic particles. 
Secondly, the application and adhesion of the seminal particles to the broken edge 
(figs. 58 to 60 g). 
Lastly, their having been seen (figs. 59, 60 A) within the ovule, imbedded in its 
substance, and surrounded on all sides by the vitelline granules. 
As I have shown the possibility and even the probability, it remains only for me 
to prove the correctness of my observations. 
That the spermatic particles seen by me (figs. 59, 60 h) might possibly have been 
external to the ovule, will naturally occur to every microscopic observer. But this 
doubt is manifestly unfounded, for many reasons. 
First. The particles (figs. 59, 60 h) could not have been lying upon the ovule, 
because vitelline granules were visible above them ; that is to say, by distancing the 
object-glass from the object, the spermatic particles became indistinct, and a layer 
of granules came into focus, entirely covering the space they occupied. 
Secondly. They could not have been below, for the ovules are much too opake to 
be seen through. 
Thirdly. The seminal particles observed were only in focus, when the margin of 
the ovule was in focus, and must therefore have been on the same plane. But, as 
the ovule is a more or less spherical body, the focus of its margin corresponds with 
