RESUMEN
Extraordinarily simple, inexpensive and easily available kymograph ink writing pen system for physiological and pharmacological recordings has been described. The writing part of the pen, consisting of a small porous fibrous writing rod to which a small spongy absorbing cylinder (as an ink container) is added, is attached to one end of a very light plastic strip of which opposite end is connected to a common mechanical lever. The function of the pen was investigated by recording spontaneous frog heart contractions in situ. The pen worked quite well and the recordings were reproducible. The pen can be interesting for researchers working in those physiology and pharmacology laboratories where more sophisticated recorders are not available, and is especially convenient for mass use in students' physiology and pharmacology labs, as alternative for smoked-drum kymograph method.