Z 
160 BOTANICAL GAZETTE. [ June, 
The employment of soft paraffin in order to make the sections ere 
as described by Schénland, is quite unnecessary, as the sections ad ere 
perfectly without this; indeed, it is much easier to get a good ribbon " 
sections without the soft paraffin than with it, owing to the difficulty 0 
perfectly removing the surplus soft paraffin—DovaLas H. CAMPBELL, 
Berlin. 
Rules for the Botanical Exchange Club.—It having been decided to 
| organize the American Botanical Exchange in connection with the 
national herbarium in the Department of Agriculture, the botanist of the 
department will act as director of the Exchange, and the following rules 
will be followed in its management until further notice: 
1, Persons desiring specimens are required to contribute a mary 
regarded as equivalent in value to those called for. The specimens wante 
in return may be selected when the others are sent or at any time after- 
ward. 
2. The number of the specimens returned will be at the pig 
of the director, and will depend on the rarity and condition of those : 
nished. In the case of well known plants they will probably nearly 
_ equal the number sent 
3. In the case of small plants, several specimens should be furnished 
: . : ; : tor 
under one number, as in such cases a single specimen is not a satisfactory 
representation of the species. 
ed specimens of all flowering plants and bene 
eived, and also specimens of thallophytes, the rs 
mentioned to be under the charge of the Chief of the section of habe cate d 
Pathology. Hereatter lists will be published of plants especially desiree, 
or of which no more Specimens are needed. “11 be 
8. An account of the Specimens received from each person he 
kept, and of those sent in return, and, also, of any other specimens ser of 
: desires or can supply. The Exchange will thus serve as a bureau 
information Upon this subject. ber 
- Conditions of membership: Any botanist may become a mem o- 
of the Exchange Club by paying annually to the director the sum of tw 
