o04 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 thrde 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 l)rown, 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 hody 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 ^'acuolated 

 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-Schonberg, 

 :03; and others). In the earthworm testis, spermatogonia and 

 spermatophore cells had degenerated, as well as the spermatocytes. 



