170 



it a Carum. My first glance suggested Sium and I said so. He 

 pointed to the jointed petioles. I said: does not my Siiim hetero- 

 phyUiLm have below its leaf-blades jointed petioles? A search 

 for my specimens showed such to be the case in that and some 

 other species of Sium; and so I wonder what conclusion he will 

 reach as to the genus. 



"August 2. Letter to Parish with names of plants identified. 

 Wrote on Necker's Cactaceae, but with little success. 



"August 3. Look up Necker's Cact. again; went into a more 

 general study of his system and terminology; rewrote one page 

 of my paper. Gave time to ... on the subject of type for 

 Linnaean Cactus, a name that should not be maintained at all; 

 showed him, out of the Philosophia Botanica that Cactus is, 

 with him, merely abbreviated from Melocactus, which later is 

 therefore the type of Cactus with Linnaeus; which is what . . . 

 wants, and this revelation pleased him. He consulted me also 

 about Dalea as a genus name, to be taken up as a synonym from 

 Linn. Sp. PL, instead of Parosela Cav. Of course, Dalea is the 

 name for the genus by simple priority, irrespective of its sup- 

 pression by Linnaeus, as I said; but I also assured him that Dalea 

 should be taken up, if need be, as prior by its place in the syn- 

 onymy of Linn. Sp. PI. 



" Received today a fine copy of Caesalpino from Junk of Berlin ; 

 also from Wesley and Son Lindern's two books on Alsatian bot- 

 any. Ordered more books from Junk. So passed the day, with 

 apparently little done, yet possibly not so little. 



"August 4. Day of indisposition. Nothing accomplished 

 but a little manual labor at books and specimens. 



"August 5. Succeeded in making an end of the paper on 

 Neckerian Cactaceae; which, when on account of Mr. . . .'s wish 

 to learn what these genera really were he induced me to under- 

 take, I thought I could do in two hours; but it is one thing to 

 ascertain the identity of Necker's groups and quite another to 

 make each case plain to the ordinary every-day botanist who 

 can read or understand nothing without the aid of an actual 

 interpreter. It is the effort to make clear to others of slow ap- 

 prehension and small learning, what is plain at a glance, that 

 ■(-akes up so much time. 



