355 Commonwealth Avenue, Boston, Mass. November 17th, 1921. 
My dear Mr. Powell: 
To -morrow I Intend to get off to you a long 
letter. This is simply a short one to tell you that I hare pre¬ 
pared a model herbarium sheet for you which goes off in the next 
mail. 
I have prepared the genus oover according to 
the system I have adopted. Of cousre it is simpler to write the 
name of the genus than to set up type for it* But I want you to 
see what I consider a model. The number before the generic name 
refers to the systematic sequence of the genus • You can, if you 
prefer, arrange your genera in alphabetical order. But that is 
not scientific. An herbarium should show relationships. The spec¬ 
imen is mounted with surgeons adhesive tape. That is the best maj 
erial as it does not crack as easily as ordinary gummed linen. 
An herbarium specimen should exhibit the entire plant. Flowers 
are not sufficient for a sure diagnosis. I have chosen one of my 
labels that indicates a critical set. It Is perhaps a little 
large for ordinary purposes. The attached field data label and 
the paper pocket complete the model sheet. The size of the paper 
is standard, also the size of the genus cover. If you copy this 
model specimen you will be in conformity with the great herbaria 
of the world. 
Yours very sincerely. 
Dr. C. r '. Powell, 
Balboa, Canal 2one, Panama. 
