586 F. A. Potts, 



tlie inner ectodermal epitlielium into the mantle cavity and sliortly 

 afterwards hatch as Cypris larvae. 



But if we do not retard the "developing- e^g-s" as a eine to the 

 reproductive processes of this Rhizoceplialan ^) we have to accoimt 

 for the practically simultaneous development of a great number of 

 heavily yolked eggs in the narrow confines of the ovary and for 

 their passage into the mantle cavity without the ageucy of ducts. 

 It seems to me a vastly more probable explanation that the ova 

 migrate into the body wall thus affording a greater opportunity for 

 the production of a large number of embryos and that they attain 

 the mantle cavity by piercing a thin ectodermal epithelium of the 

 mantle and not by the violent rupture of the walls of the visceral 

 mass. But the ultimate decision of this and other problems connected 

 with the reproduction of Mycetomorpha rests with the observer who 

 is able to obtain further material of this extraordinary creature. 

 The "developing e^g'' with its central sphere of blastomeres, the 

 peripheral arrangement of the yolk and the three or four vacuolated 

 peripheral cells very possibly represent a hitherto undescribed type 

 of development. 



The Glands of the Visceral Mass. 



Toward the anterior end of the visceral mass, the ectodermal 

 epithelium becomes modified both dorsally and ventrally over a disc- 

 like patch (Fig. K). Under a high power (PI. 16, Fig. 11) the 

 cells are seen to become fall and columnar and very numerous, each 

 section showing crowds of small deeply stainingnuclei not very different 

 from those of the ectoderm elsewhere. Towards their inner boundary 

 the cells contain a granulär substance, not stained by borax carmine 



]) It was suggested to me that these developing eggs might represent 

 some stage of a Protozoan hyperparasite but of the two gentlemen who 

 were kind enough to examine my sections Mr. K, R. Lewin of Trinity 

 College, Cambridge could find no definite evidence of their Protozoan natura 

 and Dr. HiNDLE of Magdalene College was strongly of the opinion that 

 they were not Protozoa. 



Mr. Smith teils me that in SaccnUiia after the eggs are expelied 

 into the mantle cavity a few remain in the ovary and soon degenerate 

 without fertilisation. In Miicetomorpha the bodies appear to be eggs 

 which have reached an advanced state of segmentation and so uniform is 

 the structure that I cannot suppose degeneration to have commeuced. 



