The variation in intensity has been explained recently by nonlife mechanisms for Depressio Hellespontica (an area showing one of the greatest seasonal changes) ([ref.2]). Similar nonlife mechanisms may be applicable to the other dark regions, and, thus, the "darkening" can be used only as circumstantial evidence in support of a Martian life form. If inorganic interpretations of the seasonal albedo variation are accepted, then an inorganic interpretation must also be advanced for the polarization variation. Two possibilities can be suggested: (1) A change in surface texture, caused by varying absorption of atmospheric constituents, causing both the albedo and polarization to change in the manner observed (2) A change in surface texture, in which the surface material becomes rougher, which also explains the observed polarization data ([ref.5]) The third argument against the regenerative feature of the dark areas being a life process has been advanced by Kuiper ([ref.6]). It is based on atmospheric circulation causing dust, presumably lava, to be blown on the dark areas of Mars during the late summer, autumn, and winter, and then removed during the spring. Mamikunian and Moore have recently advanced the similar explanation that carbonaceous chondrites or asteroidal matter may induce the observed phenomenon if they are abundant on the planet’s surface. The pulverized chondritic material will exhibit a high degree of opacity due to localization and, hence, a change in polarization characteristics and a decrease in polarization following mixing of the chondritic material with indigenous surface minerals. The fourth observational argument, the Sinton bands ([ref.7]), has been shown to be at least doubtful. Rea, Belsky, and Calvin ([ref.8]) recorded infrared reflection spectra for a large number of inorganic and organic samples, including minerals and biological specimens, for the purpose of interpreting the 3µ-to-1µ spectrum of Mars. These authors state that a previous suggestion that the Martian "bands" be attributed solely to carbohydrates is not a required conclusion. At the same time they fail to present a satisfactory alternate explanation, and the problem remains unsolved. More recently, Rea et al. ([ref.9]) noted the similarity between the 3.58µ and 3.69µ minima in the Martian infrared spectra and those of D₂O-HDO-H₂O mixtures and, particularly, of HDO. With all this marked disagreement in interpreting the observational data concerning Mars, it becomes clearly evident that an experimental approach to the detection of life on Mars should provide the maximum positive information possible. Some life-detection experiments developed with NASA support have been summarized by Quimby ([ref.10]).