AND ZOOGEOGRAPHY OF IXBIAN OLIGOCH/ETA. 113 



long time, and many of which miisfc have died. Very numerous 

 small morulse were budding from the body-wall, to which they 

 were all, at the stage examined, adherent. Some were also 

 budding from the surface of the alimentary canal ; and here and 

 there some were seen in the angle between strands and parjetes. 

 There was no special production in the proper genital segments 

 of the parent animal. 



Sections 7 jj. thick, stained in Delafield's hsematoxylin and 

 diflt'erentiated by a short immersion in iron-alum, dispel any 

 doubts as to the actual formation of morulse on the strands ; they 

 show that sexual cells may also be produced from the lining of 

 the body-wall, as well as — which is interesting — from the newly- 

 forming ring of cellular proliferation around the site of each 

 future fission. They also allow the history of the developing 

 morulpe to be traced. 



Text-figs. 2-6, all taken from longitudinal sections, will illus- 

 trate the various situations of origin, and wi)l supply the place 

 of further description. 



Text-figure 2. 



Proliferation of sexual cells from bodj'-wall, near a zone of budding in a 

 posterior individual of a chain. X 1000. 



The early stages in the production of morulee may be shortly 

 summarized as follows : — 



(1) The sexual cells when first recognizable as such (text-fig. 2) 

 possess large, round nuclei, close together and with a diameter of 

 7/x or rather less ; a protoplasmic covering is scarcely dis- 

 tinguishable ; in the pei'iphery of the cell the chromatin is 

 scattered, but (as seen in sections) it forms a ring near the 

 middle, the centre of the ring being clear (text-fig. 2), or more 



Proc. Zool. Soc— 1922, Is^o. YIII. 8 



