The TTL output stage is a rather complicated pushâpull circuit known as a totem-pole output (the transistors, diode, and resistor in the right-most slice of this TTL logic gate circuit). It sinks currents better than it sources current.
The theory for spontaneous generation refers to the idea that life can produced from nonliving things. Lazzaro Spallanzani proposed in his experiement that air was necessary for spontaneous generation.
The Italian scientist Lazzaro Spallanzani (1729-1799) is probably best known for his contributions to the debunking of the theory of spontaneous generation. Yet, among his various scientific interests, Spallanzani also investigated in great detail the ability of various animals to regenerate missing body parts.