At high intravesical pressure, electrical stimulation of the ventrolateral reticular formation of the rostral pons provokes relaxation of the urinary bladder in cats (Iwanaga, '61). After confirming the vesico-relaxer response a minute lesion was made electrically corresponding to the tip of the electrode and the descending degenerations were traced by the Marchi technique. From this region originate a special group of ponto-sacral connections, which, participating in the medial reticulo-spinal tract, terminates in the ventral horn cells of the lumbo-sacral division of tie cord. Lesion on one side causes bilaterally descending degeneration, the contralaterally descending component being predominant. These ponto-sacral connections have collaterals to the homolateral pontine detrusor nucleus (Kuru and Yamamoto, '64), to the contralateral ventrolateral reticular formation of the rostral pons and to the bulbar vesico-relaxer center (Kuru et al., '60), Since electrical stimulation of this pontine region results in an augmentation of discharge in the external urethral sphincter (Kuru et al., '63) in addition to vesical relaxation at high intravesical pressure, this kind of ponto-sacral connections is concluded to subserve storage of urine.