In the production of culture juices containing mitotic substances from fresh-water algae, after effecting an isolation on a medium A (given below), an exclusively mineral medium-preferably medium B (given below)-admixed with agar-agar is inoculated with the isolated strains under exposure to a powerful illumination preferably derived from incandescent (filament) lamps, for 12-15 hours out of the 24 and at a substantially constant temperature of the order of 35  DEG C. until the algae are suitably developed, the same exclusively mineral medium, preferably without the agaragar, is inoculated with the algae under substantially the same illumination and temperature conditions maintained during a sufficient period of time for the development of the algal mass, whereupon a mash of the algal mass is prepared in the same medium, e.g. using an electric mixer, the mash is inoculated in bottles containing the medium and subjected during a period of the order of 15 hours out of the 24 to illumination, for instance by means of the incandescent (filament) lamps, while the temperature is kept constant at about 35  DEG C., and the mash obtained is filtered on a sterile filter to collect the culture juices, which may then be concentrated or lyophilized.  Under preferred operating conditions, the amount of agar-agar added is within the range 8-10 grams per litre of medium, the intensity of illumination is 1500-1800 lux, there is passed through the bottles a filtered mixture consisting of 100 vols. air and 20 vols. carbon dioxide gas saturated with water vapour and flowing at a gauge pressure of 150 gm./cm.2, and the algae remaining after the filtration are isolated and desiccated for subsequent utilization.  The following Cyanophyceae algae among others mentioned, are preferably employed:  Phormidium uncinatum, Phormidium ambiguum, Cebennense brevis and Oscillatoria brevis, derived from thermal waters.  Medium a consists of the following ingredients in the specific proportions disclosed in the Specification: potassium nitrate, dipotassium hydrogen phosphate, magnesium sulphate, calcium nitrate, iron perchloride solution, extract of sphagnum (as defined), extract of garden soil (as defined) and twice-distilled water.  Medium B consists of the following ingredients in the specific proportions disclosed in the Specification: calcium nitrate, calcium chloride, calcium sulphate, magnesium sulphate, sodium bicarbonate, magnesium chloride, potassium nitrate, dipotassium hydrogen phosphate, sodium silicate, sodium nitrate, sodium phosphate, potassium chloride, iron citrate, iron sulphate, iron perchloride solution, copper sulphate, ammonium molybdate, zinc sulphate, cobalt chloride, manganese nitrate, citric acid and twice-distilled water. The lyophilized culture juice is water soluble, and incompletely soluble in diethyl ether, benzene, chloroform, petroleum ether, acetone and absolute alcohol.  A detailed example of the cultivation is disclosed. The mitotic activity of the culture juice is determined by a testing method which may involve filling to a given volume with the juices to be tested, a certain number of Petri dishes each containing a different amount of medium B diluted to 50% with twice-distilled water, inoculating all the dishes with a standardized drop of an algaltest suspension, exposing to light and to a convenient temperature, and thereafter examining the effect of the inoculation.  The algal-test suspension is prepared from a strain of Cosmarium lundellii inhibited from multiplication in the medium B diluted to 50%, except in the presence of the culture juice containing the mitotic substances.  The juices strongly promote cell-multiplication of bacterial, algal, animal or vegetable (e.g. tubercles of Jerusalem artichokes) tissues.ALSO:Culture juices containing mitotic substances are obtained from fresh-water algae (see Division C6).  The following Cyanophyceae algae among others mentioned, are preferably employed: Phormidium uncinatum, Phormidium ambiguum, Cebennense brevis and Oscillatoria brevis, derived from thermal waters.  The juices strongly promote cell-multiplication of bacterial, algae, animal or vegetable (e.g. tubercles of Jerusalem artichokes) tissues. Examples are directed to the healing of (1) an abscess in a ram, (2) gangrenous peritonitis in a female cat and (3) infectious eczema on the hind legs and tail of a female cat.  Tests have also been carried out on fistulae, lesions, varicose ulcers, scabs and wounds of human beings.  The culture should be applied under slight compression to fill up the wound and then covered with a sheet of corded sterile wadding and of gutta percha. Alternatively, the culture juice may be sprayed on to the wound or applied as a salve.