182 REPORT OF THE CONFERENCE ON GENETICS. 
cordially welcomed by an old friend, Edward Bouteiller, whose name is 
frequently quoted in the classical ‘Flora’? of Cosson and Germain. 
Together we visited numerous localities rich in varieties of the genus 
Mentha, the study of which was his favourite hobby. He possessed in 
his herbarium a considerable collection of the most instructive of the 
mints of those parts, including a series of specimens collected at various 
times, the oldest about 1830, in the same localities. A comparative 
examination of these witnesses of the past displayed an interesting fact. 
Dividing the time elapsed into periods of from ten to fifteen years, each 
one of these seemed to be marked by the appearance of certain hybrid 
forms not to be found in any of the others. Wishing to see whether 
this observation was also applicable to the more recent period, and 
accompanied by two colleagues, MM. G. Camus and Mellerio, in 1902, 
I decided once more to visit Provins, where I had not been since the 
death of my much-regretted friend, in order to revisit, after a lapse of 
eighteen years, some of the localities which I had formerly explored 
so assiduously, and to make a thorough investigation of their present 
state. Imagine my disappointment! The principal object of this present 
visit was the vicinity of the peat bog of Poigny, thus called because of 
the proximity of the village of that name, near which is found a great 
abundance of M. aquatica, arvensis, and rotundifolia, as well as of their 
hybrids. The M. Schultzii Bout. (aquatico-rotundifolia) noticed for the 
first time in 1874* on the edge of the peat-bog, and seen there again, 
though in much less profusion, in 1882, had entirely disappeared. In the 
same way we unsuccessfully sought for the forms of M. aquatico-arvensis 
and arvensi-rotundifolia, formerly noticed in this prolific place,t with 
M. rotundifolia. aquatica, and arvensis. I only saw one variety of 
M. sativa differing from all those which had previously flourished there. 
A visit to other localities brought about similar results. Everywhere the 
legitimate species alone had persisted in the midst of perpetual changes 
in their train of hybrids. 
CONCLUSION. 
According to facts observed at various times in the same localities in 
Seine-et-Marne, and covering a period of seventy years, the duration of 
the mint hybrids, varying according to circumstances, is always limited, 
and the apparent stability of MW. sativa in the neighbourhood of M. arvensis 
and aquatica is an illusion created by the continual production of fresh 
hybrid plants which succeed each other indefinitely. 
According to an interpretation of the facts which up to now is only 
based on theory, the intermediate forms uniting two species, instead of 
being hybrids, correspond to the phases of incubation of new species in 
the course of formation, issuing from the old, but deviating from their 
successive differentiations, of which the last form, after the obliteration 
of the intermediates, at length reaches a definitely fixed type. This 
hypothesis receives no support from the observations I have made in th 
genus Mentha. 
* See Bull. Soc. bot. Wr. xxii. (1875), p. 249. 
t See Malinvaud, Menthe eas. pres. gall. Nos. 29, 30, 44, 54. 
