262 



A. FELTYNOWSKI 



Fig. 1. Single-stage carbon replica of tobacco mosaic virus 

 rods showing periodic structure along the rod axis, longi- 

 tudinal structure and hexagonal cross-section. Instrumental 

 mangification 40,000. Final magnification 160,000. 



form of a "herring bone"' arrangement, (b) a longitu- 

 dinal structure running the full length of the rod, (c) 

 evidence that the cross-section of the rod is angular. 

 Many of the rods have been resolved having a 

 definite hexagonal cross-section which fit into the 

 arrangment of longitudinal structures. The periodic 

 "herring bone" structures are possibly due to carbon 

 piling up on one side of a helix when the rod is 

 lying along the direction of incidence of the evapo- 

 rated carbon. A striking feature is the regular angle 



of the periodicity relative to the longitudinal struc- 

 tures. In certain instances some of the longitudinal 

 features appear as hollow grooves at the corners of 

 the hexagonal cross-section. A through focal series 

 of electron micrographs have shown that these ridges 

 and grooves are not due to fringe effects caused by 

 focusing. 



Preparations containing both tobacco mosaic virus 

 and turnip yellow virus have been examined under 

 identical conditions to confirm that the structures 

 described are confined to the TMV. A serious limit- 

 ing factor is the presence of very small material in 

 the virus suspensions and considerable care must be 

 taken in the preparation prior to replication in order 

 to minimise these effects. 



From the preliminary work carried out in this 

 laboratory employing carbon replicas, there is some 

 evidence that the structures in TMV predicted by 

 x-ray methods may be observed in the electron micro- 

 scope. 



We are indebted to Dr. Roy Markham of the Molteno 

 Institute for supplying the purified suspensions of the 

 TMV, to Dr. V. E. Cosslett for many valuable discussions 

 and also to the Agricultural Research Council for finan- 

 cial aid. 



References 



1. Bernal, J. D. and Fankuchen, I., /. Gen. Physiol. 25, 



111 (1941). 



2. Bradley, D. E., Brit. J. Appl. Phys. 5, 96 (1954). 



3. Cochran, W., and Crick, F. H. C, Nature 169. 234 



(1952). 



4. Cochran, W., Crick, F. H. C, and Vand, V., Acta 



Crystal. 5, 581 (1952). 



5. Franklin, R. E., Nature 175, 379 (1955). 



6. Price, W. C. and Wyckoff, R. W. G., Nature 157, 764 



(1946). 



7. Sennett, R. S. and Scott, G. D., /. Opt. Soc. Amer. 



40, No. 4 (1950). 



8. Watson, J. D., Biochim. Biophys. Acta 13, 10 (1954). 



Filamentous Forms of Influenza Viruses 



A. Feltynowski 



State Institute of Hygiene, Department of Virology, Warsaw 



riLAMENTOUs fomis of infiucnza viruses were first 

 observed by Mosley & Wyckoft'(8). Chu, Dawson & 

 Elford (3) found that recently-isolated strains of the 

 A-type frequently showed filamentous forms. They 

 demonstrated that these forms were characterised by 

 several properties of the elementary bodies of the 

 influenza virus. Hoyle (7) found in the dark field of 

 the light miscroscope protrusions in the infected 

 allantois membrane and concluded that they contain 

 virus material. It was Wyckoflf (11) who first exam- 

 ined the membrane of the chicken embryo infected 



by influenza virus on thin sections and found 

 that the cells apparently excreted influenza virus 

 filaments. 



In a review of Angulo in 1951, the argument was 

 presented that the filamentous forms were no viruses 

 but breakdown products of the cell cytoplasm. In a 

 previous paper (6) this argument was proven to be 

 non-valid 



Most investigators concerned with the morphology 

 of the influenza virus have described either the ele- 

 mentary round bodies or the elongated forms from 



