544 



Journal of Applied Microscopy. 



mentous algae, except that extreme care must be taken 

 while changing fluids. It often happens that a single 

 desirable desmid appears when examining field collec- 

 tions. In such a case, remove it with a fine pipette, 

 and get it into a drop of water on a clean slide, invert 

 it over a bottle of one per cent, osmic acid for a 

 minute, leave the slide exposed to the air until the 

 water has almost all evaporated, and then add a drop 

 of ten per cent, glycerine. In a few hours (6-24), 

 put on a cover and seal. It requires more time, care, 

 and patience than it is worth to attempt staining in 

 such a case. 



PHAEOPHYCEAE. 



The brown algae are almost exclusively marine. 

 The slime, so prevalent in the group, often makes the 

 technique difficult. 



Ectocarpus. — Fix in chromo-acetic acid (twenty- 

 four hours), wash in fresh water, since the salt of 

 sea water may cause inconvenience in subsequent pro- 

 cesses. Stock material should be passed up to seventy 



lest the desmids be lost 



Fig. 21. Fucus vesiculosus. 



A. Small portion of plant showing bladders and fruiting branches. One- 

 half natural size. B. Transverse .section of fruiting branch .showing 

 oogonial conceptacles. X 6. C. Antheridia and paraphyses. From a 

 preparation fixed in chromo-acetic acid, stained in borax carmine, teased 

 out and mounted in balsam. X 255. D. Oogonium showing five of the 

 eight oospheres. Prepared as in C 



Fig. 20. Ectocarpus confervoides. 



From a preparation stained in 

 Mayer's hsmalum,and mounted 

 in glycerine. X 255. m. Multi- 

 locular sporangium, u. Uni- 

 locular sporangium. 



per cent, alcohol for safe 

 keeping. Eosin or May- 

 er's haemalum are good 

 for glycerine mounts. 

 If paraffin sections are 

 to be made, the material 

 must be brought very 

 gradually from absolute 

 alcohol into the clearing 

 agent, and from the 

 clearing agent into the 

 paraffin. 



Other filamentous 

 members of the group, as 

 well as the more delicate 

 membranous forms, may 

 be treated like Ectocarpus. 



Ei/ciis. — Fuciis may 

 be fixed, washed, and 

 preserved like Ectocar- 

 pus. It is difficult to get 

 paraffin sections across 

 the whole fertile branch, 

 but elegant sections may 

 be obtained by cutting 

 narrow strips containing 



