1914] Setchell: The Scinaia Assemblage 83 



been examined. Some work has also been done on certain type speci- 

 mens in different herbaria, hut most of siit-h woi-k was necessarily 

 snperficial. 



The general method of proccdufc, in the ca.sc of hci'l>;irium speci- 

 mens, has been, after moistening first with 95 per cent alcohol and tlicii 

 with water, to remove a sufficient portion for examination. The 

 selected portion was then soaked for some time in water, passed 

 through a strong solution of potassic hydrate, three separate and 

 prolonged washings in water, 10 per cent hydrochloric acid, then 

 three more washings in water, and finally preserved in 70 per cent 

 alcohol to which a trace of formalin had been added. The specimens 

 were finally sectioned on a freezing microtome. Througli an ingenious 

 adaptation of the freezing device of Osterhout (1896, p. 195), Dr. 

 N. L. Gardner has modified it so as to use it on the ^linot rotnry 

 microtome, thus making it possible to cut very thin and uniform sec- 

 tions. JMost of the sections used have been 5fx or lOfx thick and were 

 cut by Dr. Gardner or by Dr. T. H. Goodspeed. The stain used was 

 Fuchsin S. (Griibler's) in acidified alcohol. 



In spite of the treatment with swelling reagents, none of the speci- 

 mens was brought back absolutely to its original shape, although in 

 most cases it was possible to determine whether the specimens were 

 either cylindrical or else at least not very much flattened. 



III. MORPHOLOGY 



Tn dealing with the general matters of structure before taking up 

 the special morphology and taxonomy, it seems desirable to speak of 

 a Scinaia assemblage, because it was found on careful study that no 

 less than three genera arc i'ei)resented among tlie plants usually 

 referred to Scinaia and have the external form of that genus as well 

 as some of the histological characters. 



In habit and color there is general agreement among all the plants, 

 but there are some differences which assi.st in distingui.shing the 

 species at sight. In general the plants arise from a discoid lioldfast 

 from which one or more short, solid stipes arise which hi-inch dicho- 

 tomou.sly and fairly regularly ;ind repeatedly, to i)i'oducc a more or 

 less ample frond anywhere rrom 4 to :50cm. in heiglit. The tips are 

 even or uneven in height according, apparently, to the conditions of 



