270 GROWTH OF PLANTS 



the greater part of the relatively small amounts of non-cellulosic material 

 from the fiber membrane, had reduced the physical state of the fibers to a 

 fine white powder, but had not changed the native cellulose pattern. Three 

 years later Sisson,^^ by means of x-ray diffraction analysis, corroborated the 

 earlier work of Farr and Eckerson ^o on the presence of crystalline cellulose 

 in young cotton fibers. 



These botanical studies were of sufficient chemical interest to bring a 

 contribution from The Chemical Foundation, Inc. in 1936 for the increase 

 in staff and facilities for plant cell-membrane research. The work was 

 continued at Boyce Thompson Institute. Drs. Florence L. Barrows, Jack 

 Compton, Stanton A. Harris, Florence E. Hooper, Richard E. Reeves, and 

 Wayne A. Sisson were added to the research staff and the numbers of 

 laboratory assistants increased correspondingly. 



Studies of various types which were undertaken resulted in the publica- 

 tion of papers dealing with certain colloidal reactions of cell membranes to 

 treatment with sulphuric, hydrochloric, and phosphoric acids; ^^ the isola- 

 tion of pectic acid from the cotton fiber; ^^ the effect of certain non-cellu- 

 losic constituents upon the x-ray diagram of cellulose; ^'^ orientation in 

 young cotton fibers, as indicated by x-ray diffraction analysis; ^° a consider- 

 ation of the microscopic structure of plant cell membranes (Fig. 103) from 

 various parts of the plant kingdom in relation to the micellar hypothesis 

 of Nageli; ^^ x-ray diffraction behavior of cellulose derivatives; ^^ the dis- 

 integration of the cell membrane (Fig. 104) of the cotton fiber by a pure 

 culture of bacteria; ^^ microscopic analyses of additional cell membranes 

 from various parts of the plant kingdom; ^ x-ray analyses of textile fibers; ^^ 

 x-ray diffraction analysis and its application to the study of plant constitu- 

 ents (Fig. 105) ; ^1 the behavior of the cell membrane of the cotton fiber in 

 cuprammonium hydroxide solutions with particular reference to their dis- 

 persion, electrokinetic, and coagulation behavior; 4- 1^. 32 ^^^q lamellate 

 structure (Fig. 106) of certain plant cell membranes; ^ and the structural 

 relationship of rayon to natural cellulosic fiber materials, as sho^\^l through 

 a study of the viscose process.^ The studies of the behavior of cell mem- 

 brane materials in cuprammonium hydroxide and m the carbon disulphide 

 used in the viscose process showed that in both instances the cellulose par- 

 ticles are dispersed, not dissolved, in the medium, and that the non-cellu- 

 losic materials present in small quantities in the cotton fiber membrane 

 play a part in bringing about this dispersion and in producing the final 

 viscosities of the mixtures. These observations are in keeping with the fact 

 that highly purified cell membranes of cotton fibers lose their viscosity- 

 producing power in many reagents, although the nature of their cellulosic 

 component remains relatively unchanged as observed microscopically and 

 examined by means of x-ray diffraction (Fig. 107). 



Observations on the membranes of epidermal cells of the Avena coleop- 

 tile revealed another different inter-particle relationship. ^^ In the cotton 

 fiber and wood fiber, where fibrils constitute a unit of structure, the end-to- 



