To my mind these experiments suggest that the reproductive habits of both species, if closely observed, will be found to be subject to considerable variation, and I think it not impossible that each species is, especially in confinement, capable of being a good deal deflected from its normal behaviour. Moreover, there seems to me no great improbability in the idea that there is an interdependence between the number of young and the stage of maturity in which they are born. But, at the same time, the case as told by Kammerer strikes me as proving too much. If each species is so sensitive to conditions that the normal procedure is gravely modified in one generation, and if that modification can reappear in a pronounced form in the next generation without a renewal of the disturbing conditions, it becomes extremely difficult to understand how the regularity which each species is believed to display in nature can be maintained. Surely both species might be expected to be in confusion. From a passage in Kammerer's earlier paper (1904, p. 55) on the subject, I infer that he also would expect considerable irregularity in the natural behaviour, but that he has not investigated the point.[20] 3. _Modification of the Colour of Salamandra maculosa induced by Change in the Colour of the Soil on which the Animals were kept._--Kammerer speaks of this as the most convincing of all his experiments on the transmission of acquired characters. So far, however, no full account of them has been published.[21] The statement is that when salamanders are kept in yellow surroundings the yellow markings gradually in the course of years increase in amount relatively to the black ground colour. Conversely by keeping the animals on black garden soil, the yellow may be greatly diminished in quantity until it largely disappears. (The account in _Natur_ adds that very moist conditions also favour the increase of yellow, and that with less moist conditions the yellow diminishes.) From each kind, the (induced) yellower and the (induced) blacker, a second generation was raised, on soil of neutral colour, and each family was later divided into two parts, half being put on black and half on yellow ground. As regards the offspring of those which had lived on _black_ soil no positive result had been reached up to the date of publication, but it is stated that these young resembled their parents in having the yellow distributed in _irregular spots_. As regards the offspring of those which had lived on yellow soil the account follows up the story of that part of the offspring which were put on yellow soil again. It is stated that these, though derived from parents with irregular spots, _developed the yellow as longitudinal bands_.