A New Method for the Study of Chromosome 

 Rearrangements and Plotting of Chromosome 

 Maps 



T. S. PAINTER 



Reprinted by author's and publisher's permis- 

 sion from Sciet2ce, vol. 78, 1933, pp. 585-586. 



A contributio?! to sciejice ca?i be made ifi many ivays. I have 

 pomted out examples of three different kinds of scientific paper in 

 the previous pages of this collection. Faintefs paper represe?its still 

 another kind, for it is a report on the discovery of a 7iew techjiique 

 a?id the light throw?i on proble?ns of lojig standing as a consequence. 

 The existeiice and activities of the ejilarged, elongated, midtiple, 

 salivary gland chromosomes, and the facility with which they can be 

 studied utilizing Paintefs techtiiques, have led to increased knowl- 

 edge of the structure of chromoso?nes a?7d their behavior at rneiosis. 



A thorough review of the hiowledge gained from the use of this 

 technique is given by Pai?iter in his paper, ''Salivary Chromosomes 

 and the Attack on the Ge?ie,'' Journal of Heredity, vol. 2S, 1934, pp. 

 464-476. 



It has long been known that in matrix. The same chromosomes, or 



the functioning salivary glands of characteristic parts thereof, may easily 



manv^ dipteran larvae the chromosomes be recognized in different cells of an 



show an elongated and annulated individual, or in different individuals 



structure. For the past year the writer of a species. If the position of one or 



has been studying such chromosomes, more segments is shifted, by some 



principally by the acetocarmine form of dislocation (translocation, in- 



method, in larvae of Drosophila mela- version, etc.), the exact morphological 



nogaster. From this study the follow- point (or points) of breakage can be 



ing conclusions are warranted: determined and the segments iden- 



(1) Each of the chromosomes has a tified in their new position. This dis- 



definite and constant morphology and covery places in our hands, for the 



is made of segments, each of which first time, a qualitative method of 



has a characteristic pattern of chro- chromosome analysis and once the 



matic lines or broader bands, which normal morphology of any given ele- 



appear to run around the achromatic ment is known, by studying chro- 



161 



