JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS condition, as far as the net is con- cerned, remains the same up to some certain point (time), after which in case (a) it continues the same, in case (b) the cell then dies off, while in case (c) the cell, having overcome its interfering influences, starts to grow again. All three are considered as bacteriostatic up to the point where these changes occur. Then (a) continues as bac- teriostatic, (b) becomes germi- cidal, and (c) returns to normal. A standard growth curve is presented also so as to show the comparison with how the same bacteria would grow if no toxic substances were present to interfere with their nor- mal growth processes. fering with the metabolism of a bacterial cell so as to prevent the latter from functioning normally. Besides interfering with the repro- ductory processes, the prevention of the formation of chemical by-prod- ucts which may produce undesirable conditions within the medium (e.g., the cosmetic product) is also an end product of this phenomenon. For our purpose here we will con- sider a bacterium as being composed of a mass of colloidal material called protoplasm contained within a thin differentially permeable membrane, which substance contains the living material of the cell. It is comprised of carbohydrates, lipolds, proteins, hormones, vitamins, enzymes, water, CHART GROWTH AN0 BACTERIOSTASIS CURVES CURVE I = NORMAL "GRowTH CURVE", SHOWING (A) THE LAG PHASE r (8) PosITIVE GROWTH PHASE r (C) LOG PHASE OF ACCELER- ATE0 GROWTH• (D) RESTING PHASE r (g) LOG DECLINING PHASE OF ACCELERATED OEATH• AND (F) THE DEATH PHASE, CURVE 2 = TRUE I•ACTIrRIOSTASIS, CURVE • .- IIpSEUDO-I•ACTERIOSTASI.5"' ("A"' = OELAyL O LAG PHASE) AN0 ("l•" = INCREASED KILLING CURVE 4 = GERMICIOAL CURVE, Bac'rERza A•TD THEZR LZ•E PROCESSES Thus far we have seen that bac- teriostasis is a phenomenon which involves a chemical substance inter- and a variety of inorganic constit- uents. To maintain their existence these bacteria utilize food in a man- ner quite similar to that as used by humans. Chemicals are brought into their environment which they

?'digest, first through enzyme at- ?tachment followed by penetration •!:i:,.i: through the cell membrane into i:: • the interior, where it is made use of, as in man, to furnish the necessary i f'energy requirements of the cell to !'i•':: do its work and for the building ma- ?:.'1111 terial needed to add new cellular i': i: structure or to repair damaged or ji: worn-out ones. These cells manu- ?facture their own enzymes within i',t?• their structure and apparently bring :i!i'•'some of them to specialized points ß ?on the cell surface. Within the cell 7!i.lthere is also a specialized struc- ?•!!.: ture, called the nucleus, in which the i::.vital processes of reproduction are .:.i.øriginally carried out. Around this ß C n A .'r 3. :. DETERMINING BACTERIOSTATIC POTENCY OF CHEMICALS 397 cause it is, basically, action at one or more of these three points-- namely (X) the extra-cellular en- zyme at the cell membrane surface, (Y) the intra-cellular enzyme or "a semivital constituent" in the cytoplasm, and (Z) the "vital es- sence" or "gene-equivalent" in the nucleus that determines if we have, respectively, bacteriostatic, pseudo- bacteriostatic, or germicidal action involved. Bacteria grow (i.e., reproduce) by the process of simple fission. One cell goes through the necessary systematic internal changes so that the original one nucleus be- BACTERIOSTASIS •NO TwE BACTERIAL CELL M NUCLEUS AND ITS •'4UCLEOPLASM •VITAL CENTERi• ENZYME OR ESSEN- ENZYME TIAL ELEMENT OF CYTOPLA•M nucleus there exists a membrane to protect it and to separate it from the rest of the cell. The protoplasm of these two parts, which make up the complete cell, are called, respec- tively, nucleoplasm and cytoplasm. This picture has been drawn be- comes two. Then, the cell having swelled, elongates, synthesizes the necessary component parts, pinches off at the center, and two daughter cells are thus formed. Interfering with this process is the basic bac- teriostatic phenomenon.