Introduction to Animal Morphology. 83 



minute anal opening described by Corda, Lcydig, and 

 Hancock. A second race of buds may form on the 

 growing bud before its detachment : indeed, as many 

 as five such progenies have been found united. This 

 process is frequent in summer. 



Sexual reproduction is commonest in autumn, but 

 is not confined to any season. The spermigenous 

 organs form near the base of the tentacles (Fig. io,sp.} 

 At one spot, the interstitial ectodermal cells enlarge, 

 and become polyhedral, and with them are found 

 amoeboid cells. The neighbouring neuro-muscular 

 cells thin out, and form a coating over this now conical 

 or wart-like growth. The nuclei in the altered cells 

 disappear, and their contents become granular and 

 confluent. Then from the amoeboid cells, oval re- 

 fracting spermatozoa (Fig. n, B) form, and become 

 flagellate, and escape into the surrounding water 

 through an apical opening in the papilla. 



ova also develop in the interstitial tissue, near the 

 proximal or aboral end (Fig. 10, o). There, in one or two 

 separate projections of the ectoderm, cells increase, and free 

 nuck-i appear in the surrounding intercellular protoplasm. 

 In each projection, one central, amoeboid, vacuolated cell con- 

 taining granules and vitellin particles increases in size, and a 

 nucleus or germinal vesicle appears within it, around a 

 ;iinal spot (Fi,u r . n, C). < irren pigment grains, and 

 iharply-contoured, round masses (pseudo-cells), like the yelk 

 >f a spoirjilla-cL^, develop within thiseell. After these 

 form, thr germinal v.-siele heroines indistinct. They are fer- 

 tili/rd /'// si/u, the head of tin- spermatn/uuii touching the outer 

 wall : whereupon the yelk segments, each part 



ID8, and tin- egg 1" < "incs a mortila, 



whox- inn. : :i;il and the outer cylindrical. 



month, then becomes 

 .-li with irregular px -, and dark. The cylinder cells 



G 2 



