Nixie IC Pin why would it be connected?
It can't work without a ~5V Vcc on the chip, and a ground. 

Since you say it was removed from a (presumably functional) instrument, let's assume it did work.

So, perhaps you simply can't see the power connections or they are no longer present- they are under the chip, or it is a 4-layer board with ground and power planes, or some of the parts you removed were effectively or literally shorts to the power rails.

Edit: Also note that these chips (both the 74x and the Russian one) are among the few TTL chips (as is the 7490) that don't have the power pins in the corners- they're pin 5 (+5) and pin 12 (0V).