364 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the bodies of the young were less than half that of the old, they must 
have absorbed more radiation in proportion to their volume than the 
adult. The irregularities in the effects produced by like exposures. 
must be due to differences in the animals, since the character of the 
exposure was unvarying. | 
The degenerative changes found at the three stages are similar, 
and so may be described together. An excess of pigment was ob- 
served in the body wall in a number of cases. One small adult at 
the end of four and a half days had turned a reddish brown, markedly 
darker than the color of any other animal; several other worms showed 
coloring of less intensity. The pigment which produced the coloring 
occurs normally in the body wall, but in small amounts. A micro- 
scopic examination shows it among the connective-tissue cells in which 
the circular muscle cells are imbedded. Inasmuch as blood sinuses 
appear in the same regions when the body wall happens to be gorged 
with blood, and pigmentation is often produced by blood, it seems. 
probable that the pigment in these spaces is haematogenic. 
The testes of copulating worms were strongly affected by the rays. 
There was an entire loss of spermatogonia and a scarcity of the first 
spermatocyte stage. Their places were occupied by vacuolated 
spermatophore cells, whose nuclei showed chromatolysis. Some 
nuclei of the primary spermatocytes, and possibly of spermatogonia, 
were represented by swollen or shrivelled nuclear walls containing 
no chromatin. I did not find the degeneration in its early stages. 
The elongating secondary spermatocytes and the contents of the 
seminal vesicles appeared normal. In parts of the testis a condition 
of their further degeneration was found in which some chromatin had 
gone into solution. In the testis of a copulating worm which had 
died as the result of radium treatment less than two hours before it 
was put into a fixing fluid, most regions of the germinal tissue were a 
mass of cell debris devoid of chromatin. Here and there the sperma- 
tocytes of very resistant tubules were indicated by rounded cells. 
whose nuclei stained deeply in haematoxylin. Spheres unstained by 
haematoxylin were present and were taken to be the archoplasmic 
masses. The other tissues of the animal showed no evidence of 
degeneration previous to death. 
It has been found that the beta radiations of radium, as well as 
X-rays, are especially destructive to the spermatocytes of the mammal- 
ian testis (Thaler, :05; Thies, :05; London, :05; Albers-Schénberg, 
:03; and others). In the earthworm testis, spermatogonia and 
spermatophore cells had degenerated, as well as the spermatocytes. 
