Experimental Growth in Animals 235 



100 



200 



500 1000)f 2000 



10 20 doses SO 



pjg 9.9— Seminal vesicle test with various androgens. Amplification of the number 

 of visible mitoses by colchicine. {After Dirschel et a\.*") 



dence ot an indirect action via pitiiiiaiy stimulation."^ The same ap- 

 plies jMobably for the increased mitotic activity detected in the thy- 

 roid of female rats injected with testosterone.*'"' 



The mitotic activity of the parathyroid glands of mammals is 

 usually very low, and is difficult to study; hence, the utility of colchi- 

 cine. FoUiculin (estradiol) and progesterone injections in the rat 

 result in the appearance of many mitoses.^- This eflfect may be the 

 consequence of hypocalcemia. The contrary, hypercalcemia, proba- 

 bly explains why irradiated tachysterin (Holtz's A.T.IO) decreases 

 the parathyroid mitotic activity. Testosterone injections increase mi- 

 toses in this organ; this may be an indirect effect mediated by the 

 pituitary.^^ 



