Posted on 21 April 2015
There are three Russian nesting dolls (Matryoshka) with the following text:
- 26 сентября 1849
- 31565 дней
- выделять слюну
Left one is a birth date.
The middle means 31565 or 86 years (the time a person lived until 27.02.1936).
The right one means "to allocate saliva" so we guess "salivating", which would lead to a dog experiments which lead to the discovery (or invention) of classical conditionalism.
The article in Maddox Clipping