GERM CELLS OF ANURANS 245 
undergo degeneration owing to fragmentation of the centrosome 
and consequent formation of polyasters which lead to aberrant 
divisions. Practically all of the first generation of male germ 
cells, i.e., those derived from the primordial germ cells of the 
entoderm ridge, pass through this abortive larval sexual cycle 
and degenerate in the act of division. A few of these cells give 
rise by direct transformation, without the intercalation of the 
first or second maturation division, to gigantic spermatids with 
axial filaments. Such spermatids possess fourteen tetrads. A 
very few of the primordial germ cells fail to pass through the 
precocious maturation cycle, and probably persist unchanged, 
apparently giving rise later by repeated division to a second gen- 
eration of germ cells in the male. It may be remarked here that 
many cells of this second generation look as if they take origin 
from germinal epithelium elements, i.e., appear to be transformed 
mesothelial cells. This point, however, is still under investiga- 
tion as morphological methods are not sufficient to determine 
whether or not such transformations actually occur. The mode 
of origin of the definitive germ cells of the adult is not strictly 
germane to this particular paper, and the question must be left 
undecided, pending results of experimental investigation. 
This second generation of male sex cells, and this is the impor- 
tant point here, no matter whether they be lineal descendants of 
the primordial germ cells or transformed mesothelial elements, 
undergo a second maturation (sexual) cycle in larvae just 
ready for metamorphosis, i.e., in second-year tadpoles, and this 
generation of cells, oddly enough, gives rise to normal sex prod- 
ucts, spermatids, and spermatozoa. The maturation cycle is 
normal in every respect. From the time of metamorphosis on to 
sexual maturity the young male frog apparently ripens his sex 
products continuously — this despite the fact that for a year or 
so, owing to his small size contrasted with that of mature females, 
he is probably unable to copulate. 
It will be recalled that in the female sexual cycle the stage 
corresponding to the first spermatocyte division of the male is the 
stage of polar body formation which occurs normally at the time 
of copulation, presumably several years after metamorphosis. 
