638 



Journal of Applied Microscopy, 



wall. For sporophytes of Marchantia it is better not to cut the whole receptacle, 

 but rather to remove the branches so that they may be cut separately. For the 

 very best preparations of mature sporophytes it will pay to trim away the 

 gametophyte structures, leaving only enough to show the foot with a few of the 

 surrounding cells. Sections 5 /< or 10 /< thick can be made without much 

 difficulty from material prepared in this way. 



Among the Bryophytes no other form affords such an excellent opportunity 

 for studying the development of spores as Anthoceros since a single longitudinal 

 section of the sporophyte may show all stages from earliest archesporium to 

 mature spores. For studies like A and B, chromo-acetic material cut 10 // 

 thick and stained in Delafield's haematoxylin is very good, but to bring out 

 details of the chloroplast Flemming's weaker solution gives better results. The 

 starch grains in the chloroplasts take a beautiful violet color with the safranin- 

 gentian violet-orange combination. It is very difficult, however, to bring out the 

 details of nucleus or chloroplast on account of the minute size of these structures. 

 The drawings from which C and D were reproduced were made with a one- 

 sixteenth oil-immersion objective. The drawings, like all the others illustrating 

 the Bryophytes, were reduced one-half by photography. 



MUSCI. 



Material for a study of the mosses is much more abundant, and a series of 

 stages in the development of the various organs is easily secured, but it is much 

 more difficult to obtain good preparations 

 because so many of the structures are hard 

 to cut. Chromo-acetic acid is to be recom- 

 mended as the most satisfactory fixing 

 agent, but where structures are refractory 

 and very likely to make trouble in cutting, 

 it will often be found more satisfactory to 

 use picric-acetic acid in the 70 per cent, 

 alcohol, since material fixed in this reagent 

 does not become as hard or as brittle as 

 that fixed in any of the chromic acid series. 



Antheridia. — It is easy to find material 

 for a study of antheridia, because, in so 

 many cases, the antheridial plants can be 

 detected at once without even a pocket 

 lens. Fnnaria, with its bunch of antheridia 

 as large as a pin head, is extremely com- 

 mon everywhere. Spring is the best time 



to collect it, but it is found fruiting in the autumn and sometimes in summer ; 

 besides, it is easily kept in the greenhouse, where it may fruit at any time. 

 Mnimn has a still larger cluster of antheridia, which may be seen at a distance 

 of several yards. Polytrichum also has a large cluster of antheridia surrounded 

 by reddish leaves, so that the whole is sometimes called the moss " flower." In 

 making preparations of Polytrichum these colored leaves should be carefully 



B 



Fig. 7. 



Archegonia of Webbera candicans. X 104. 



Celloidin section, 20 microns. B. Young 



antlieridia of Polytrichum commune. X 420. 



