If you ever doubted if this city has a heart, here’s proof that it does. Moved by the story in Monday’s edition of The Indian Express on Jaswantlal Sarvaiya, a 63-year-old kidney donor who needs Rs 85,000 for life-saving surgeries, dozens of people, from businessmen to senior citizens, have called in to help, including a surgeon who has offered to do the operations for free.‘‘This man donated his kidney to a stranger for free. Today, if he has to beg, it’s an insult to humanity,’’ said Dr Arun Ranade, who runs a nursing home in Panvel. C.K. Patil, secretary of the Matoshree Vriddhashram (an old age home), said he was considering giving Sarvaiya a place to live after his surgeries. ‘‘We might give him accommodation,’’ he said.Several diamond merchants also called to ask how much money Sarvaiya still needs. A retired Thane resident wanted to give Rs 200, and wondered if his donation would be accepted. He has been donating Rs 200 to Rs 500 every month to sick people.In 1976, Sarvaiya had come to Mumbai from his hometown of Bhavnagar to donate a kidney to a man he had never met. The recipient’s father had then offered him Rs 50,000 but he refused.