It is the assessee who is in full possession of facts regarding the true character of the amounts and the sources from which they v/ere derived and Section 106 of the Evidence Act casts on him the burden of proving what lies within his special knowledge.
S. Kumaraswami Reddiar vs Commissioner Of Income-Tax on 20 March, 1959
take a look at judgement here : http://www.lawweb.in/2012/03/burden-of-proof-is-on-assessee-to-prove.html
The ratio in the said judgement referred to by you should be understood in that context. There were deposits in the bank. It is assumed that the depositor was the assessee himself or he knew who the depositor is. In the circumstanes it is assumed that assessee is fully aware of the source of the funds.
The requirement under the IT Act is in the circumstances spelt by Courts that the assessee should discharge his primary onus i.e. name and address of the depositor, hiis Pan and bank details etc. since the assessee would have full knowledge of these details. It is for the Department to prove that the transaction is not genuine thereafter.