Spermatocytes of Lasiopogon (Diptera). 373 



tion of B. acidophilus milk and lactose. This corroborates the 

 work of Rettger and Cheplin. 



The normal subjects as well as the psychotic patients receiving 

 treatment, gained in weight; but while the latter were improved 

 physically, there was no improvement in their psychoses. 



The intestinal flora becomes transformed on treatment with 

 B. acidophilus whole milk and lactose, but the relative percentage 

 of gram-positive rods rarely exceeds 70 per cent. 



Incubating B. acidophilus whole milk at room temperature is 

 satisfactory for only a few days, after which the number of viable 

 organisms decrease rather rapidly and the acidity increases to 

 the point of unpalatability. 



181 (1928) 



Observations on the behavior of the nucleus and chromosomes in 

 spermatocytes of Lasiopogon (Diptera). 



By CHAS. W. METZ and JOSE F. NONIDEZ. 



[From the Carnegie Institution of Washington, Cold Spring Harbor, 

 N. Y., and Cornell University Medical College, New York City.] 



In the primary spermatocytes of Lasiopogon (species not yet 

 determined) the earliest growth stages resemble those in other 

 asilids {e.g., Asilus sericeus); 1 but before growth has progressed 

 very far, the nucleus, which previously has been approximately 

 spherical, becomes irregularly invaginated and evaginated. The 

 nuclear membrane appears to push in around the chromosome 

 threads and the latter to push out into the cytoplasm; so that 

 soon each thread (bivalent) lies in a lobe or pocket, isolated to a 

 great extent from the others. The nucleus becomes converted 

 almost entirely into lobes, which follow the contour of the chromo- 

 somes and ramify in various directions through the cytoplasm. 

 There is no uniform configuration ; the chromosome threads are long 

 and slender, and often follow a tortuous path, apparently at ran- 

 dom save for a slight polarization toward the nucleolus. 



As growth progresses the chromosome threads condense and 

 shorten, and coincidently the lobes become less ramifying. This 



1 Metz and Nonidez, Jour. Exp. ZooL, 1921, xxxii, 165. 



