Ahstraet-It
IS shown that srmrlarly to the movement m capdlartes, also m other dtspersrve systems, the drstrnction between the concentratron of solute in resident fluid and m gurd flux has to he made Introducmg this concept to the dispersion equation, both for the injection and detection modes, a better understanding of the physrcal meanmg of the known solutions as well as the new ones can be obtamed It IS also shown how parttcular sohrtrons are related by known and new transformations Time and spatral moments of all solubons as well as changes of time moments are given To make the paper more general all the consrderatrons are performed in normal time and space v&rinables However, a change to dunenaonless vanables, generally apphed m chemmai engmeermg, can be performed at any stage The paper deals only wath solutrons for lnfinlte and semi-mfirute media m the case of a conservatrve tracer However. there IS no doubt that the apphed concept may be extended to other cases The drlTerences between the solutrons for different mJectron-detection modes are essential m cases of low Peclet numbers It IS shown that the theory of age-&stnbuUon functions apples only d the tracer is mjected and measured m flux