656 RECORD OF CURRENT RESEARCHES RELATING TO 



Medusa as one of the Tracliomedusns, thougli it is quite a jieculiar 

 form, and very possibly is either the isolated representative of an 

 archaic type of that order or has degenerated in connection with its 

 exceptional life-conditions — those of fresh water. 



Professor Lankester is fully satisfied that Limnocodium develops 

 directly from the egg. When specimens are kept living in a glass 

 jar under constant observation it is found that exceedingly small 

 specimens make their appearance amongst the larger ones. The 

 youngest which he has seen at present measured only -^^ inch in 

 diameter, and others were under observation very little larger. 

 The smallest was of a subspherical form, without any aperture to the 

 ectodermal investment. Four minute tentacles were sprouting near 

 one pole of the spherical body, and between these rudiments of four 

 others were seen. Within — the sub-umbrellar musculature was 

 already developed and contracting at intervals. The four radial 

 canals were also present, and, what is more remarkable, the sub- 

 umbrellar cavity was already well marked, and within it the manu- 

 brium with the oral aperture. Yet the margin of the umbrella was 

 still closed by a continuous ectodermal coat which, when perforated, 

 would become the velum. 



These minute embryos correspond very closely in appearance 

 with the embryos of the well-known typical Trachomedusan Geryonia, 

 as figured by Metschnikoff.* They leave no possibility of supi)osing 

 that Limnocodium has, like most Leptomedusfe, a hydroid trophosome. 

 In respect of its development as in other respects, Limnocodium is not 

 more closely allied to the Leptomedusae than to the TrachomedusEe, 

 but is one of the Trachomedusge. 



A remarkable fact which is not yet explained, is the excessive 

 rarity of females. All the specimens which Professor Lankester 

 examined have been males. Females clearly enough must be present, 

 or have been present among the shoals of males — wlicnce the embryos 

 discovered by Mr. Sowerby. It is a known fact among Trachyline 

 Medusae that in some species males are excessively abundant, and 

 even in some sj)ecies females have never been detected. Thus again 

 Limnocodium agrees with the Trachyline Medusae. 



The exceedingly important fact that some of the Coelentera and 

 lower kinds of worms digest their solid food by the inception of the 

 solid food-particles into the substance of endodermal cells, each cell 

 behaving as an Amoeha, has now been fairly established by the observa- 

 tions of AUman on Myriotliela, Metschnikoff on Turbellarians, and 

 T. J. Parker on Hydra. Limnocodium exhibits this mode of digestion 

 in the most striking and obvious manner, the endodermal cells of the 

 stomach showing with a power of 800 their amceboid character, and 

 showing further the presence of such food-bodies as Protococci, dia- 

 toms, and Euglence in various stages of digestion within the proto- 

 plasm of single cells and of aggregated groups of such cells. 



At the meeting on June 17 of the Linnean Society at which Pro- 

 fessor Allman's paper was read, it was suggested that a compromise 

 should be effected between the two names proposed, and that the 

 * ' Zeitsclir. f. wis?. Zoologio,' xxiv. pi. ii. fi.2;s. 12 and 15. 



