1.1.68 अणुदित्सर्वस्य चा अप्रत्यय:

The literal meaning is - अप्रत्यय: अणुदित् सवर्णस्य स्वस्य च. The following definitions are necessary for the sutra.

1. An अप्रत्यय is the de-suffixed part. For example, in इको यणचि, इक् is being de-suffixed  i.e. replaced by the suffix यण्.
2. अण् is a प्रत्याहार
3. उदित् (उत्  इत् ) implies "उत्s as इत् " - i.e. कु,चु,टु,तु,पु (5x5=25 letters)

The sutra implies that the de-suffixed parts and the अण्s would eclipse (or swallow if you will) their सवर्णs. For example, in रमा ईशः or माला छ (मालीयः), the आ is eclipsed.

1.1.67 स्वं रूपं शब्दस्याअशब्दासंज्ञा

Except as शब्दसंज्ञा, the शब्द shows its own स्वरूप (form). The application of prefixes/suffixes that change meaning on a word act upon the meaning/sense/form of the word not on the word itself.