148 THE PLANT WORLD. 



cilia and the other of cilioles (fig. 5). The prolongation of the pedicel 

 through the center of the capsule makes the columelJa, but this can only 

 be seen in cutting the capsule open. The spores are found mixed with 

 various delicate hairs inside the capsule. 



After the student has demonstrated the presence of, and become 

 familiar with the parts of a moss plant as al)Ove outlined, he may wish 

 to compare it with a description of the species he has in hand. For 

 this reason it is perhaps best to begin with a nanied specimen. Such a 

 specimen can easily be procured, often by simply enclosing a stamp, 

 from some well-known student of mosses,^' By comparing this, part 

 by part, with a good description of their species they will have some- 

 thing definite to start from. Unfortunately the literature at present 

 available on our mosses is scattered and not thoroughly abreast of pre- 

 sent knowledge. We are promised a moss flora of the Eastern United 

 States by a well-known specialist, but it is not yet ready, and almost 

 the only thing is Lesquereux and James' Ifosses of JSortli America. 

 This work is illustrated by the clapper plates, showing all the North 

 American genera, that accompanied Sullivant's account of the mosses 

 in the second edition of Gray's Manual^ published in 1856. This book 

 is provided with artificial keys, by the aid of which the student will 

 soon be able to locate at least any genus he is likely to meet with. He 

 may expect to have difiiculties and perplexities in studying mosses, but 

 they are no greater in their way than those surrounding the study of 

 many a group of flowering plants, and when once the ice is broken he 

 will find opening before him a wide and interesting field. 



COLLECTING SETS OF PLANTS FOR EXCHANGE. 



By A. S. Hitchcock. 



ANY educational institutions with limited funds at their dis- 

 posal for herbarium purposes are able to augment their col- 

 lections by exchanges. The same is often true of the amateur 

 who is accumulating a private herbarium. While the latter may be 

 able to exchange upon the basis of desiderata chosen from lists, the 

 curators of herbaria in public institutions rarely have time for this but 

 prefer to make "blanket" exchanges. For these reasons and others 



M 



*The editors of 'Flic Plant World will take pleasure in having a specimen 

 determined for an\' of our readers who wish to take up the study of mosses. 



