and Laboratory Methods. -2075 



time. By throwing the sections into cold water, the plant tissue usually separates 

 readily from the hardened paratfin and may be examined at pleasure. 



In making the paraffin blocks, a plate of heavy glass is selected which is 

 about one foot square. Around the margin of this glass plate, on one surface, 

 are cemented strips of glass one inch wide and one-eighth of an inch thick. 

 Melted paraffin, of the proper degree of hardness for sectioning work, is then 

 poured upon the leveled plate until it floods the plate to the top of the marginal 

 glass strips — i. e., until the paraffin is one-eighth of an inch thick over the entire 

 surface of the plate. When sufficiently cool, the paraffin is marked into checks 

 of any required size with the point of a scalpel, so that the entire sheet of paraf- 

 fin will readily break into squares of the proper size when cold. A ruler is used 

 in checking off the surface. If one of the marginal strips of glass is left so that 

 it can be removed when the paraffin is cold, the latter may be more readily freed 

 from the glass, Newton B. Pierce. 



U. S. Depart, of Agriculture, Pacific Coast Laboratory and Gardens, Santa Ana, Cal. 



Collecting and Preserving Fungi. 



UREDINEAE. 



The methods used to prepare tirst-class specimens of the flowering plants 

 are mostly applicable in collecting the Uredineae. The same care in changing 

 driers is needed to produce attractive specimens. The best method is to use a 

 portfolio or press in the field, and to arrange the specimens as soon as collected. 

 Only a few driers should be carried, as the specimens will keep for a day in the 

 sheets of thin paper. 



Where it is windy or large quantities are to be collected a botanical box is 

 convenient to carry specimens for a short time. Many grass leaves will curl if 

 not attended to very soon after gathering. I prefer to cut the leaves of grasses 

 and sedges into four-inch pieces when collected, and to discard those not much 

 attacked by the rust. Pieces of this length are more readily kept flat. The 

 ligules of grasses, and portions of the inflorescence of both grasses and sedges 

 should be included whenever possible so that the determination of the host plant 

 may be verified. Great care should be taken in collecting to find the uredo and 

 aecidial stages, as in many cases the uredosori offer much better distinctive 

 characters than the teleutosori. The aecidia should be collected when the cups 

 have opened, and before they are so old that the borders and spores have mostly 

 disappeared. As they are often somewhat fragile, better specimens can be 

 made by applying only sufficient pressure to keep the leaves flat. In all cases 

 the host should be accurately determined. Many serious errors have been niade 

 on account of carelessness in this. In some cases the teleutospores are to be 

 found on the stems, when uredospores only occur on the leaves. This is par- 

 ticularly true with the species of Phragmidia on Potentilla, early in the season. 



I think that there is only one method of arranging the specimens in a collec- 

 tion of any size, and that is according to the host plants. I use the standard 

 herbarium sheets and enclose the specimens in packets which are fastened to 



