BOT.-VOL. II.] HUS-PORPHYRA. 231 



The Indians of the slopes of the Pacific Coast also use 

 Porfhyra as a food, the tribes making yearly trips to the 

 seashore to collect it, along with other economic seaweeds. 



VI. Methods. 



On account of the fact that in most of the species of 

 Porfhyra examined the jelly makes up a large part of the 

 frond, considerable difficulty was encountered before the 

 writer finally succeeded in preparing the necessary number 

 of mounts. The specimens collected fresh were either 

 dried or killed on the shore in Flemming's mixture, strong 

 and dilute, one per cent, chromic acid, one per cent., two 

 per cent, and five per cent, chrome alum, Wilson's corro- 

 sive sublimate, one per cent. formaHn and alcohol. Of all 

 these, Wilson's solution, formalin and alcohol, gave the 

 best results, the others either shrinking the specimens or 

 failing to fix them. As soon as this point was settled, all 

 except the latter three were discarded. In some cases, as 

 in P. naiadmn, formalin gave the best results; while in 

 others, Wilson's solution was to be preferred. 



The necessity of the salt of a heavy metal to fix the jelly 

 became apparent when rough dried and herbarium speci- 

 mens were examined. The first ones to be studied were 

 dried specimens of P. -perforata which, when soaked in 

 water, resumed their original outward form. But when the 

 same process was tried with others, especially with P. 

 variegata, it was found that the jelly dissolved very readily, 

 so that some means had to be resorted to by which the 

 specimens might be preserved in good condition. At first, 

 glycerin, twenty per cent, glycerin in water, and twenty 

 per cent, alcoholic glycerin were tried, but without good 

 result. Finally Professor Setchell suggested the use of a 

 saturated aqueous solution of corrosive sublimate. When 

 used cold, this answered all requirements in every case ex- 

 cept that of P. variegata, where it was necessary to use a 

 boiling saturated aqueous solution. 



Of all species of which fresh material could be obtained 

 sections of from three to five microns in thickness were 



