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covering a properly formed body of loose absorptive cotton with the thinnest 

 rice tissue paper (2), On top of the pad is laid the sensitive paper (3), of 

 course face up. On this follows the moss (4), and over all a piece of thin 

 (one-fourth inch) plate glass, very carefully cleaned (5). By means of a 

 framework, which passes across ends of the glass (6) and bolts with nuts, 

 the board at the back and the glass are drawn closely together. By tighten- 

 ing the nuts sufficiently with a bicycle wrench, a very close contact may be 

 obtained. The apparatus is then placed in the sun, great care being taken 

 that the glass intercepts the rays of light at exactly right angles. 



The printing is allowed to go on until a sufficiently sharp print of the 

 moss is made on the solio paper. Some care is necessary at this stage, since 

 over-exposure leads to the "printing out" of the thinner parts of the plant 

 and a consequent obscuring of the form of the more delicate parts. By a 

 little practice one is able to decide just how long a given specimen should be 

 printed. This is a matter which concerns the individual specimen, and no 

 tw^o subjects can be treated exactly alike. 



After the print has been made, the usual toning and fixing takes place, 

 the result being a negative print. In order to obtain a positive print, this 

 negative may be soaked in some clearing agent (the writer usually uses 

 kerosene) and used as a negative, as if it were a glass negative. Of course, 

 care must be taken to avoid a surplus of kerosene. Thus from the paper 

 negative any number of positive prmts may be made. 



As will be readily seen, this method is adapted for the reproduction of 

 labels, autograph notes, plates, and anything which is printed on but one 

 side of the paper. The writer has found this method extremely useful in 

 reproducing plates from rare works and in multiplying drawings of various 

 structures or other features desired. Some may chose the positive print, in 

 w^hich case, as is , usual in illustrations, the object appears dark against a 

 light background. (Plate IV. i). The writer, however, prefers the negative 

 print as having greater sharpness. (Plate IV. 2 and 3) 



The accompanying plate illustrates the two types of prints, and it will 

 be noted that, while the positive print reminds one of the usual illustrations 

 more strongly than does the negative print, the latter is perhaps a trifle 

 sharper in its details. 



As the reader will observe, this method is capable of adaptation in 

 almost an endless number of ways, and will be found applicable not only to 

 solio paper but also to blue-print paper, and other kinds of printing paper. 

 It is extremely useful as furnishing to the worker a rapid method of making 

 an accurate record of the habit and size of rare specimens which he may be 

 able to see occasionally. It is perhaps as a means of making such a record 

 that this method finds its greatest usefulness to the working bryologist. 



Should readers of The Bryologist desire further information than this 

 outline sketch furnishes, the writer would be very glad to communicate with 

 any such and explain further such points of difficulty, as he may be able. 



Bureaic of Plant Industry, Waskingtojt, D. C. 



