Dougal I imdcrtool^ the cytological stud)- of the two forms of 

 Stigcocloiuimt. ( )\viiig to the minuteness of the cells, I could 

 not satisfactorily cany out the study, yet I think I obtained a 

 few points of interest. I ani under j^'reat oijligation to iJr. Mac- 

 Dougal for his kindly suggestions and criticisms, and also to Dr. 

 Livingston, who not only has put some of his materials and solu- 

 tions at my disposal, but also has given me much invaluable 

 information. 



I. Methods 

 l^oth the palmella and filamentous forms were examined in 

 the living state. Especially was the transformation from one 

 form to the other carefull)' studied. After several fixing fluids 

 had been tried, I found that Boveri's picro-acetic acid proved 

 better than any other. This, therefore, was used almost ex- 

 clusively. All the preparations were stained /// toto with 

 borax-carmine ; the sections were stained either with Auerbach's 

 fluid (mixture of methyl green and fuchsin S) or with iron-alum- 

 haematoxylin. To make total preparations of the filament, the 

 following method was used. A clean cover-glass was touched 

 on the surface of the water in a culture dish, where the filaments 

 were floating. Then the cover-glass was dipped in the fi.xing 

 fluid, which killed and fastened the algae at the same time. To 

 obtain the total preparations of very young filaments, a drop of 

 weaker solution was put on a cover-glass and a few palmella cells 

 were kept in this drop for a week or so until the young filaments 

 reached the two- or three-celled stage. Then all the solution was 

 drawn off by means of filter paper, and the cover-glass was put 

 in fixing fluid, which, as already stated, fixed and fastened the 

 algae. To cut filaments into sections the following devices were 

 used. A piece of Ulva, which had been preserved in alcohol, 

 was washed with water and was fastened with albumen on a 

 cover-glass. Then the Ulva was touched to the surface where 

 filaments were floating and the cover-glass with the Ulva was put 

 in the fixing fluid. After being clarified, the Ulva pieces with algae 

 were peeled off from the cover-glass and cut into sections. 

 The palmella cells were wrapped up in frog's epidermis to be cut. 



