In case of proprietory business the individual is the sole person of carrying on hte business, so everything is assessable in his hands only. However if there is a transfer of business, then the transferee is the sole responsible person.
In your case father has transferred the business to son. Father has carrie don the business till mid of the eyar & the remaining half si being carried on by the son. So there will be 2 B/S & P&L's one in th father's name till Apr11-Sep11 & the other in the son's name from Sep11-Mar12. Father is eligible to claim entire depreciation as tehre is no provision under the I-T Act to claim proportionate deprn unline under the Co's Act. Son will be eligible to claim 50% of depreciation as the business is ebing carried on by him for 6 months.