/!' MINNESOTA BOTANICAL STUDIES. 



face. The color is uniformly a very dilute green. The gelati- 

 nous thallus is firm and slippery. 



A species of BalbochcBte was found very commonly growing 

 as an epiphyte on the plant, being attached by a sort of sub- 

 spherical cell imbedded in the gelatinous mass of the Stapfia 

 thallus. Diatoms and desmids were also found in great num- 

 bers in the interior of the thallus. 



The material used for this study was preserved in 2 per cent, 

 formaline and as a consequence was rather unfavorable for cyto- 

 logical investigation. 



After washing the material for about thirty-six hours in 

 water, it was passed through the usual series of alcohols and 

 xylols into paraffine. The plants were permitted to remain in 

 each for a short time only, as they were very prone to grow 

 hard and brittle, especially if left too long in the higher per 

 cents, of alcohol or in xylol. The material was suitably im- 

 bedded for securing both longitudinal and transverse sections. 

 The sections were mounted in series and cleared in the usual 

 manner. 



After trying numerous stains, it was found that gentian violet 

 and Bismarck brown were the most useful. A concentrated aque- 

 ous solution of the Bismarck brown was used and the mounted 

 sections were allowed to remain in this for about two hours. 

 Only a 2 per cent, aqueous solution of the gentian violet was 

 used and the slides were left in the stain for about three minutes. 

 Canada balsam was used as the mounting medium. 



The cross-sections disclosed some very interesting foldings of 

 the gelatinous membrane, which cause the perforate appearance 

 seen in the diagrammatic sketch of the transverse section (PI. 

 AVI., Fig. 4) and also in the longitudinal section {PL XVI., 

 Fig. 6). The cross-section reveals no particular method in the 

 grouping of the cells in the gelatinous structure. The cells are 

 distributed in a single peripheral layer. They appear to be in 

 groups of two and four for the most part, but also in threes and 

 singly in the older thalli. 



The longitudinal section (P/. XVI., Fig. 7) does not differ in 

 essential features from the transverse, although the folds are 

 much more clearly distinguishable. This cut also shows clearly 

 the sort of alveolar structure of the interior of the thallus, of 

 which I have been unable to find an)' mention in the descrip- 

 tions of either Stapfia or Tetraspora. This may be the adapta- 



