X-RAY MICKOSCOPY 



PLANT MICRORADIOGRAPHY mann photographic emulsion and exposure 

 Plant cell research in recent years has ^^"^^ ""^^^ '-^^ l«"g '-^^ ^^^'" hours". This author 

 contributed greatly beyond its own specific published a beautiful cross section micro- 

 field to important de\elopments in biology radiograph of Sambucus pith at a magnifica- 

 as a whole, such as bacteriology, virology, ^^^^ ^^ ^^0 diameters. The physicists Barclay 

 antibiotics, tissue cultures, tumors and ge- ^^^ ^^^^ Leatherdale (1948-1951) (3) dis- 

 netics. And yet botanists have not utilized covered with soft x-rays spots in the leaves 

 to any extent x-ray methods in their research °^ many plants. These authors deduced 

 work, with the possible exception of diffrac- ^^^^^ ^^" ^^^ distribution in autumn of min- 

 tion on membrane and fiber structure study. ^^^^ deposits of high atomic weight elements, 

 Generally plant cell mechanisms are better ^"^ ^^^ ^he development of plant galls. This 

 known because of greater cell size and re- early work created a true interest in the 

 sistance in plant tissues than is true for application of the microradiographic tech- 

 animal or human cells. Now with the de- ^ique to plant problems, but during this 

 velopment of the several techniques of x-ray Period of about 40 years metallurgical, zoo- 

 microscopy, stimulated by the successes of logical and medical progress was consider- 

 electron microscopy including scanning and ^^^^^ greater than in the science of botany, 

 television recording of cell images, there are ^^^ ^^^^ P^^^ decade workers have presented 

 great possibilities of satisfying the needs of ^^^^ P^^^^t examples indicative of decisive 

 plant biology. improvements. Following Lamarque (1936) 

 History. In the past half century physi- ^^^ whose microradiographs attained high 

 cists and chemists by their fundamental in- quality with x-rays generated at 7 to 10 

 vestigations have enabled development of ^^' ^^ ^^ ^^^ "^^ ^ud 10 to 30 min. expo- 

 x-ray apparatus, and have established the ^^^^' mention is made of the application of 

 laws of penetration of x-ray beams through ^ similar technique to materials similar to 

 thin samples, the preparation of suitable P^^^^^ specimens, such as paper, by Pel- 

 specimens, the interpretation and compari- groms (1952) (7): contact method 3-15 kV, 

 son of images on photographic films, and 10-20 m.4, 5-60 min. exposure, X50 mag- 

 diverse applications. To measure plant mi- uification, opacifying solution iodine, speci- 

 croradiographic progress since the first ^^^^ thickness 30 /x. Clemmons and Aprison 

 attempts, it suffices to survey the steps from (1953) (5) undertook to develop the use of 

 1913 to actual contemporary results ob- ^°^* x-rays generated at still lower voltages 

 tained with thin sections. When Goby (1) especially in biological research. These au- 

 announced both the origination and the pur- ^^^"^^ devised apparatus so that vacuum was 

 pose of a new technique by these words: maintained around the specimen in order to 

 "Microradiography must be able to permit reduce exposure time to a tenth of that 

 observation of internal structures of small ordinarily required and thus to enable the 

 objects too opaque to be observed in the production of 10 or more historadiographs 

 (optical) microscope", he proposed several P^^ ^°^^- Moreover the excellence of the 

 potentially successful types of materials; images permitted quantitative analysis of 

 among them a Diatomea was the first plant specimens. 



specimen microradiographed. The character- Mitchell (1954) (6) used microradiography 



istics of his apparatus and technique, how- on natural samples such as elm leaves with 



ever, were not mentioned. The second sue- galls and mineral deposits, and wheat grains 



cessful accomplishment with plants was infested by weevils. His advice was that 



made by Dauvillier (1930) (2) with a Lipp- results were no better than those of ordi- 



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