Which type of pipette is distinguished by a cylindrical glass bulb near its center?

The type of pipette that is distinguished by a cylindrical glass bulb near its center is the volumetric transfer pipette. This design serves a crucial function: the bulb allows for the accurate transport of a specific volume of liquid. The bulb's uniform diameter helps ensure that the liquid can be drawn up to the calibration mark with precision, which is essential in quantitative analysis where exact measurements are required.

Volumetric pipettes are designed to deliver a fixed volume of liquid with high accuracy and minimal error. Unlike other types of pipettes, which may be used for various measurement applications, volumetric pipettes are specifically calibrated for a single volume and are ideal for preparing standard solutions in clinical and laboratory settings.

The cylindrical bulb's design contributes to the ease of filling and emptying the pipette, as it facilitates the smooth aspiration and dispensing of liquids. This level of precision and specificity is what sets volumetric transfer pipettes apart from the other options listed, making them the correct choice in this context.