Journal of Applied Microscopy. 



639 



removed after the material has been gotten into 70 per cent, alcohol. A single 

 antheridial plant of Polytrichum often furnishes a fairly complete series of stages 

 in the development of antheridia. In all cases the stem should be cut off close 

 up to the antheridia, for many of the moss stems cut like wire. It is not neces- 

 sary to use celloidin for antheridia, nor is it desirable, except where sections 

 from 20 }x to 50 // thick are wanted for habit work. 



Archegonia. — Since the necks of the archegonia are usually long and more 

 or less curved, it is necessary, for habit work, to cut sections as thick as 20 |< or 

 30 }.i in order to get a view of an archegonium in a single section, Celloidin is 

 better for such preparations, but for the development of the archegonium, the 

 oosphere, the canal cells, and also for the process of fertilization, it is better to 



JOUR.flPP.MlC. 



Fig. 8. Funaria hygrometrica. 



A. Apex of young sporophyte showing endothecium and amphithecium. X 420. 



Chromo-acetic acid and Delafield's haematoxylin. Ten microns. B, C, and 



D, transverse sections of a sporophyte of the same age as A, taken 



at three different levels. X 255. Ten microns. 



use paraffin. For the thick celloidin sections the material may be stained in 

 bulk in alum cochineal, but thin paraffin sections should be stained on the slide 

 with more critical stains. 



The sporophyte. — It is often difficult to get good mounts of sporophytes. 

 In the younger stages the calyptras are likely to interfere with cutting, while in 

 the older stages the peristome or hard wall of the capsule occasions the trouble. 

 If an attempt is made to remove the calyptra in young stages, like A of the 

 figure, the apex of the sporophyte usually comes with it. While picro-acetic 

 acid material cuts more easily, chromo-acetic acid followed by Delafield's haema- 

 toxylin gives so much sharper differentiation in stages like those shown in Fig. 8, 



