178 R. VENDRELY 



cells of Fasciola hepatica, reported that the DNA content of the nucleus was 

 more variable during intense metabolic activity than in the quiescent state. 

 In an extensive study of nuclear size and nuclear content of DNA on various 

 tissues of male, female and worker honeybees, Meria and Ris^^* report a 

 high degree of polysomaty in these tissues; they found a rough correlation 

 between the degree of ploidy and the secretory activity of the cells. 



On the other hand, Leuchtenberger et al}'^^ studying cytophotometri- 

 cally the nuclei of dwarf mice with a recessive hereditary anterior pituitary 

 hypoplasia, found a lack of the multiple DNA classes which are normally 

 present in certain tissues of rodents and other mammals. Treatment of such 

 dwarf mice with anterior pituitary growth hormone restored the DNA 

 classes completely. 



Pathological Tissues. In pathological conditions the DNA content of the 

 nucleus is sometimes affected. White et al}'^'' in an extensive chemical study 

 of bone marrow cells with special reference to pernicious anemia found that 

 the average value for the DNA content of marrow cells differs significantly 

 from the normal only in the megaloblastic anemias; the possibility of poly- 

 teny is considered in this case. Bader^"* in four types of tumors foimd higher 

 values of DNA distributed in classes and attributed this fact to mitosis and 

 polyploidy. Kasten,!"^ on the other hand, reports that four strains of mice 

 differing in susceptibility to mammary cancer have the same DNA content 

 per nucleus in the adrenal cortex, but two showed slight differences. In ex- 

 perimental tumors in rat liver Thomson and Frazer^* found a higher pro- 

 portion of class I nuclei (diploid), while regenerating liver contained an in- 

 creased proportion of class III nuclei. In an extensive study of malignant 

 human tissues, Leuchtenberger et al.^^° showed a certain deviation in the 

 DNA content of the nucleus interpreted on the basis of mitotic activity. 



In the nuclei of rectal polyps, Leuchtenberger"' found an amount of 

 DNA higher than the characteristic amount of normal nuclei. This seems 

 to be in correlation with the occurence of a great number of mitotic figures. 

 In senile keratosis, Leuchtenberger and Lund"- found that, in the typical 

 lesion, the content of DNA in the nuclei varied indiscriminately from nor- 

 mal to very high values. Pasteels and Bullough"^ also found an increase 



'"^ M. R. N. Meria and H. Ris, Chromosoma 6, 522 (1954). 



1"® C. Leuchtenberger, H. F. Helweg-Larsen, and L. Murmanis, Lab. Invest. 3, 245 



(1954). 

 i"' J. C. White, I. Leslie, and J. N. Davidson, /. Pathol. Bacieriol. 66, 291 (1953). 

 108 S. Bader, Proc. Soc. Exptl. Biol. Med. 82, 312 (1953). 

 '«« F. H. Kasten, Records Genet. Soc. Amer. 22, 81 (1953). 

 "0 C. Leuchtenberger, R. Leuchtenberger, and A. M. Davis, Am. J. Pathol. 30, 65 



(1954). 

 "' C. Leuchtenberger, Lab. Invest. 3, 132 (1954). 



"2 C. Leuchtenberger, and H. Z. Lund, Cancer Research 12, 278 (1952). 

 "3 J. Pasteels and W. S. BuUough, Arch. biol. {Liege) 64, 271 (1953). 



