The hérédité en mosaïque is the particular way of hereditary transmission which translates itself by the juxtaposition of the parents' corresponding characters on the child.
Discovered and studied by CHARLES NAUDIN from 1852 to 1865 it includes some typical examples, from which the hybrid origin is strictly established (Datura stramonio-laevis, Linaria purpureo-vulgaris, Mirabilis longifloro-Jalapa) and M. BLARINGHEM add many cases to them examinated in particular in this note (some hybrids between Hordeum distichum nutans and H. distichum erectum, between Hordeum distichum and H. tetrastichum; Pirus Bellverianum [Bollwiller Pear], sterile hybrid between Pirus and Sorbus).
The presumate sexual hybrids, as the Cytisus Adami, Crataegomespilus Dardari and Asnieresii, the Orange-trees Bizarria, the almond-peach tree and so on, whose origin is badly known, can get in.
Last, the vegetal chimerys, realised by M. H. WINKLER, between Solanum and Lycopersicum, M. L. DANIEL's graft hybrids, are following the rules of particulate inheritance, and some mutations, as the Pelargonium zonale with its leaves bordered with white, and a few other steaks partially hereditary, can be joined.
In all these cases, the individual is a compound of texture belonging to two different species that might be recognised to a certain age, at their shape, their colour, their particular mode of growth and strugling all the time to disengage themselves from each other. It is a living mosaic composed with discordant, specific elements straitly mixed in the beginning of the life, but trying to disjoin themselves, to localize themselves on the differents parts, with the time. This localisation is helped by pruning, by stumps divisions, by repeated cuttings: it accentuates when approaching the time of flowering, of the formation of the ovuls and the pollens corns; but, in the mean time, it is not necessary complete.
The hérédité en mosaïque, called still hérédité naudinienne is submitted to two rules:
1° The first hybrid generation's F1 uniformity;
2° The return to the species from the second generation, and sometimes ever since the first generation.
These rules are intended for the complicated hybrids, between very divergent species, with partly unfruitful descendance, — whatever the sexual affinity of the crossed forms might be, that the possibility of grouping all divergent characters of the parents by couples, that dominance and recessivity exist or not. The hérédité naudinienne, restricted by less conditions than the hérédité mendélienne, is governed not by rigorous laws as this one, but by rules; and it can be seen that it contains the hérédité mendélienne as a particular case.
NAUDIN has recognised, since 1865, the possible return to the parents of the hybrids, from the second generation. MENDEL, in 1865, made the same discovery, but presented it under a simplificated form and particularly lucid; he had therefore to limit a great deal his observations, field.
MENDEL limited his study to the cases where the parents differences can be paired, with one's dominance on the other. He admitted besides: 1° that in the characters separation, there are as much ovules in one part, as much pollen corn in the other part, which return to one and the other type; 2° that the pollen corn's affinitys for the ovuls are equal for any possible combinaisons; 3° that all the combinaisons are followed by the same fecondity.
It can easily be understood why several authors have restrained the domain of the hérédité mendélienne to the crossing between varieties of the same species indefinitely fertile, equilibrated, when the domain of the hérédité naudinienne is much larger and even might be more extended, with some precaution to the progeny of chimery individuals which are not real hybrids. J. L. B.