Why Hydathodes are referred as water stomata? can other things, like gases never pass through them?

Dear student,
Hydathodes are referred to as water stomata because water ooze out from the pores called hydathods. Hydathodes are involved in guttation process which is quite different from transpiration. Gases can not pass through hydathodes because there is no regulation for opening and closing of hydathodes, it remains always open. 

Regards