This is regarding the spelling of the 3-rd-Person Singular form of verbs which take the final "S".  
In the table below, the handling of the first 2 is simple, but it is the last 3 which trouble me.  

Q. Since the plural of the noun changes the form substantially, what about the inflective form in the 3-rd-Pers Singular: is it like the plural noun or is it simply with an added "S"??

ENGLISH = The Plural /vs/ the thrid-person-singular inflection
Singular   Plural        I/You      /_HE_/
Shake      Shakes     Shake      Shakes
Slice        Slices        Slice         Slices
Try          Tries         Try           Trys
Fly           Flies          Fly           Flys
Empty     Empties     Empty      Emptys

I am quite mystified in looking at your chart. Either I’m reading this wrong, or you have singular and plural mixed up.
/Legislators legislate/ is correct english, but by your chart it looks like it would be /Legislators legislates/, which is clearly wrong.
I think also I may have misunderstood your question, but I will take a stab at this too:
I slice / We slice
You slice / You slice
He slices / They slice

The third person singular does thus have the -s at the end.

Hugh is wondering how to spell the 3rd person singular forms. The "slice/slices" etc. are nouns, if I understand his post.

He tries many times, but his tries are in vain.
When he flies, he is bothered by flies.
He empties the empties.

I doubt that anyone would accept "flys, emptys, trys".

Olowkow got it exactly right. We have to differentiate between nouns and verbs. Unfortunately, sometimes they can look exactly the same. Third person singular verbs generally take the -s. That’s a good rule. Nouns take the -s as a plural form. Thus, perhaps, the confusion.

Welcome to the Agora, hugh.

- PW  

However, in addition to the -s, the rule is that the -y changes, to -ies.  It doesn’t matter if it’s a noun or a verb.

-Tim

Hugh, check this post by Katy.  ;)