HARDWICKE'S SCIENCE-GOSSIP. 



51 



peristome ; and with tliem also maybe placed the 

 calyptra : should the cost of these be an object, a 

 cheaper substitute may be found in shallovr, black- 

 ened pill-boxes. 



To preserve the leaves in an expanded state we 

 may employ the fluid media used for vegetable 

 tissues, or, when time is of consequence, llimming- 

 ton's glycerine jelly is a convenient material in 

 which to mount them, a ring of dammar cement 

 being first placed on the slide, and within this the 

 liquefied jelly, to which the expanded specimen is 

 quickly transferred, and the cover securely sealed 

 by gold size. Preparations of this kind are of the 

 highest value as types for comparison with actual 

 specimens we may have for determination. 



Fig. 34. Cern'odoii purpureus. 

 a. Male plant. 1. Leaf and its areolation. 2. Capsule. 

 3. Calyptra. 4. Two teeth of the peristome. 



2. In mounting specimens for the herbarium, 

 we must be guided by the limits which we have 

 fixed on for the extent of the same ; and I may 

 first describe the method adopted for my own 

 collection. Every species has a separate leaf of 

 cartridge-paper measuring 14ixl0| inches, and 

 on this the specimens are fixed, each mounted by a 

 little gum on a piece of toned paper ; thus 4 or 6_to 

 12 specimens, according to size, arc attached to 

 each leaf, — varieties have one or more additional 

 leaves ; and to each is also fixed a triangular enve- 

 lope, inclosing loose capsules and leaves for ready 

 transfer to the microscope, and also a label in- 

 dicating the name, habitat, and date of collection. 

 A pink cover for each genus includes the species, 

 and a stout millboard cover embraces the genera of 

 each family, with the name of which it is labelled 

 outside, the whole shutting up in a cabinet. 



Another form is that seen in Rabenliorst's Bry- 

 otheca Europpea, quarto volumes of 50 specimens, 

 one occupying each leaf, and so arranged that the 

 specimens do not come opposite to each other. 

 Others again use loose sheets of note-paper, within 

 each of which a single specimen is mounted ; but 

 this, from their size, is very cumbersome. Or we 

 may take a single well-chosen typical specimen and 

 arrange many species on a page, as is seen in the 



beautiful volume of Gardiner's "British Mosses " or 

 Mclvor's " Hepatica; Britannica;." Wiiatever plan 

 we adopt, our specimens, once well dried and kept 

 in a dry place, are unchangeable, and are always 

 looked upon with pleasure, each recalling some 

 pleasing associations, or perchance reminding us of 

 some long-lost friend, in companionship with whom 

 they were collected or studied. A stock of dupli- 

 cates must also be reserved, from which to supply 

 our friends, or exchange with other collectors for 

 desiderata in our own series : these may be kept in 

 square cases of various sizes, cut so as to allow the 

 edges of the top and sides to wrap over the other 

 half folded down on the specimens. 



The Hepatica; of the family Jungermaniacere arc 

 treated precisely as mosses, the capsules, however, 

 show but little diversity, and will not require sepa- 

 rate preservation ; but the elaters, or spiral threads 

 accompanying the seeds, are elegant microscopic 

 objects. The Marchantiacea; must be pressed when 

 fresh, as they do not revive with the same facility 

 as other species, owing to their succulent nature 

 and numerous layers of cells. 



Classification. — On this I have fully treated else- 

 where ("The Moss World," Popular Science Re- 

 view, Oct., 1871), and it may suffice here simply to 

 indicate the families of British mosses and their 

 mode of arrangement. The cell-texture of the leaf 

 takes an important place in the characters, and in 

 accordance with this principle the Cleistocarpous 

 or Phascoid group is broken up and distributed in 

 various families. We have tv\'0 orders; one in- 

 deed, comprising only the genus Aiidrecea, is distin- 

 guished by the capsule splitting into four valves 

 united at apex ; the other, including the bulk of 

 the species, has in most cases a lid, which sepa- 

 rates transversely, and usually discloses a peri- 

 stome of tooth-like processes. The structure of 

 these teeth again enables us to form three divisions. 

 In the first they consist of amass of confluent cells ; 

 iu the second, of tongue-shaped processes, composed 

 of agglutinated filaments ; and in the third, of a 

 double layer of cells, transversely articulated to 

 each other, the outer layer composed of two rows 

 of firm coloured cells, the inner of a single series of 

 vesicular hyaline cells, on which the hygroscopic 

 quality of the tooth depends. 



Sub-Class SPHAGNINiS. 



Bog Mosses. 



Earn. 1. — Sphagnacese. 



Sub-Class BRYIN^. 

 Prondose Mosses. 

 Order 1.— Schistocaupi. 



Earn. 1.— Andreseacese. 

 Order 2.— Stegocaupi. 

 Div. 1.— Elasniodontes. 



Earn. 2. Georgiacese. 



D 2 



