But we must return to the _Peridermium Pini_. It will be remembered that I expressed myself somewhat cautiously regarding the _Peridermium_ on the leaves (var. _acicola_). It appears that there is need for further investigations into the life history of this form, for it has been thought more than probable that it is not a mere variety of the other, but a totally different species.
Only so lately as 1883, however, Wolff succeeded in infecting the leaves of _Senecio_ with the spores of _Peridermium Pini_ (_acicola_), and developing the _Coleosporium_, thus showing that both the varieties belong to the same fungus.
It will be seen from the foregoing that in the study of the biological relationships between any one plant which we happen to value because it produces timber and any other which grows in the neighborhood there may be (and there usually is) a series of problems fraught with interest so deep scientifically, and so important economically, that one would suppose no efforts would be spared to investigate them: no doubt it will be seen as time progresses that what occasionally looks like apathy with regard to these matters is in reality only apparent indifference due to want of information.
Returning once more to the particular case in question, it is obvious that our new knowledge points to the desirability of keeping the seed beds and nurseries especially clean from groundsel and weeds of that description: on the one hand, such weeds are noxious in themselves, and on the other they harbor the _Coleosporium_ form of the fungus _Peridermium_ under the best conditions for infection. It may be added that it is known that the fungus can go on being reproduced by the _uredospores_ on the groundsel plants which live through the winter.
In St. Genevieve and Cape Girardeau Counties, Mo., in the Niagara limestone is found a handsome marble of a variegated liver color. Near Sheppard Landing it is 80 feet thick, and at Janis Mill, in St. Genevieve County, Dr. Shumard speaks of beds of fine texture and various shades of flesh, yellow, green, pink, purple, and chocolate, all handsomely blended.
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