I. FANKUCHEN AND H. MARK 



question. More recent papers exhibit an awareness of this fact; and 

 it may be expected that much of the forthcoming work in this field will 

 utilize not only the modern developments of technique but also those 

 in interpretation. 



In technique, the new approach starts, properly, with the speci- 

 men. While some protein fibers (wool, silk) can be handled with 

 ease, the study of others (like muscles) must be accompanied by extreme 

 precautions to prevent any appreciable changes from their natural 

 state. Because the use of normal specimens usually introduces many 

 fibers into the x-ray beam, the tendency is to reduce the size both of 

 the specimens and of the x-ray beam. This trend can be carried to 

 quite an extreme degree so that single fibers and beams of 0.05 mm. 

 diameter have been used (16); the results indicate that even much 

 finer beams could be economically employed. When the specimen is 

 a single intact fiber, the x-ray diagram is free from the possibility of 

 disorientation due to lack of parallelism between the individual fibers 

 making up a bundle. 



More and more intense sources of x-rays are being made avail- 

 able to the investigator and these are shortening the time required to 

 obtain an x-ray diagram. A more exciting possibility arises from the 

 introduction of Geiger-Muller counters to record the scattered radiation. 

 This innovation permits the almost instantaneous determination of the 

 intensity of scattered radiation and will allow the planning of many 

 experiments which are impossible by photographic methods. Studies 

 of structure as a function of time (a contracting muscle, perhaps) could 

 be made now that a continuous recorder of scattered radiation is avail- 

 able. It will also be possible to study specimens which deteriorate 

 rapidly. 



Efficient monochromatization of the x-ray beams will also be 

 useful in many cases. Biological specimens often give poor x-ray dia- 

 grams regardless of technique; and the additional background due to 

 incomplete monochromation may be enough to obscure important 

 details in the x-ray diagram. 



The interpretation of the data is also being steadily improved. 

 Increased use of reciprocal-lattice concepts and the more widespread 

 realization of the shortcomings of ordinary fiber diagrams {i. e., 

 diagrams from specimens which possess orientation with reference 

 to one direction only) lead the experimenter to attempt to prepare 



