MEMORIAL OF CHARLES A. DAVIS 19 



appears rather suddenly in the Menominee Valley, not very far north of Lake 

 Michigan, and its place is taken among the maples by yellow birch. 



"Relative to the plants I collected on my last trip into that region, I have 

 them here and am perfectly willing to send them to j^ou as soon as I can pack 

 them up. There are quite a lot of them and from a good many localities along 

 the western end of the peninsula in the Menominee Valley, as well as in other 

 places. I probably shall never make any use of them, and after you get them 

 you can verify them and either incorporate them into your own collection or 

 send them to the university, as you see fit. About the last time I ever saw 

 our friend, Wheeler, he came up to my house and went over these plants and 

 named them, or such as I had not named, and verified my names. I presume 

 some of the names are still wrong, but you can get them straight. I have 

 taken out a large series of Woodsias which I collected to have them worked 

 over here by Doctor Maxon, of the National Herbarium, who expects sometime 

 to monograph the genus. Any duplicates you find in these lots you may dispose 

 of as you see fit. 



"I hope I shall get time within a week or so to begin to send you these 

 plants, but it will depend on how well Mrs. Davis keeps. There will be several 

 good-sized bundles of them, and some of them are not in the older State lists 

 from the Upper Peninsula, or at all, if I remember correctly. 



With regard to a speech at the opening of the Hood Natural History 

 Mnseum at Alma College^ he writes, on October 9, 1899 : 



"I am, however, very greatly obliged to you for taking the opportunity to 

 say what you outline, for it will be no end of a help to the cause in more ways 

 than one, and will carry weight and have a force that anything which I might 

 say, just a common barnyard servant of the college, could not possibly have. 



"I am glad for that reason also that you have decided to say more than a 

 few words. I think your 'orphan asylum for neglected idols' excellent and 

 trust you will not forget to bring it in, for we have had a few lone and bat- 

 tered gods from the heathen world offered us already and, while something 

 can imdoubtedly be made of them in time, I wouldn't care for too many of them." 



Vegetal Origin of Limestones 



About 1897 cement factories in Michigan started up with a somewhat 

 unhealthy growth, using various clays and an unconsolidated limestone 

 that they called "shell marl/' but which did not answer to the dictionary 

 definition of marl, as it contained little or no clay ; nor did it seem to be 

 composed of comminuted shells. 



Knowledge of its true production by means of the Charas or stoneworts, 

 aided by algas, was Davis' first great contribution to American geology. 

 The vegetal origin of limestones, accepted almost at once and widely for 

 these Pleistocene limestones, is only gradually winning its proper place 

 as a key to the origin of many, and perhaps especially the Precambrian 

 limestones. Davis was much pleased when Walcott took this view. 



