46 C. 0. Whitman 



contained three lufiisorigens , from tvvo of wliich arose tlie longer , and 

 from the other the shorter tract of cells. One free nucleus was probably 

 concealed among the closely packed cells, and thus escaped notice. 



b. A Transitional somewhat less advanced than «. The anterior 

 portion was much stretehed, and so the length conld not be ascertained; 

 but the posterior portion appeared not to have thus sufifered. 



At a distance of 1 mm from the bind end occurred a large free nu- 

 cleus (.08 mm X .05 mm) : in front of this, extending 1.20 mm, was 

 an Infusorigen with its two series of germs in all stages of develop- 

 ment. Next carne a long tract of cells, extending through 3.90 mm, 

 densely packed towards the middle ; then a tract containing only two 

 free nuclei : and finally, in the anterior end, another active Infusorigen 

 with adjuncts similar to those seen in the posterior Infusorigen. 



There were 7 free nuclei in this individuai. The germ-cells of the 

 central tract varied from .004 mra to .008 mm. 



This specimen differs from a in that only one of the three Infuso- 

 rigens has been replaced by loose germ-cells. Most of the smaller indi- 

 viduals were pure ßhombogens ; but some of these also were in dififerent 

 stages of transition. 



7. D. moschatum from E. moschata, April 13. This large Ele- 

 done contained many Rhombogens and Transitionais, but, so far as seen, 

 no Nematogens with vermiform embryos. 



One individuai contained only numerous germ-cells from .004 mm 

 to .008 mm in diam. ; in another the germ-cells measured .006 mm to 

 .01 mm, and many were in process of division. In nearly all cases 

 where only numerous germ-cells were present , there were several free 

 nuclei. 



In one individuai 2 mm long, I found two fully developed Infusori- 

 form embryos, numerous germ-cells of the vermific order scattered from 

 end to end, tour free nuclei, and, near the bind end, a free germogen 

 with its residual nucleus. 



This Dicyemid had evidently passed a Rhombogenic stage repre- 

 sented by two Infusorigens. 



As to the number of free nuclei , although I have never counted 

 more than nine in any Nematogen, I think it probable that the number 

 may in rare cases be as high as seventeeu, as I have seen one Rhomb- 

 ogen with eight Infusorigens and nine free nuclei. 



As cases of transition occur not only among the shorter individuals 

 but also among the very longest , we may infer that the Substitution of 

 the Nematogenic for the Rhombogenic mode of reproduction does not 



