Encystment o/' vEolosoma. 15 



Evchytra'us given by d'Udekem (on p. 9 of separate copy of 

 his memoir already quoted) the two processes at either end of 

 the cocoon are extremely nulimentar}'. In another memoir * 

 published about this same time, dealin<^ principally with the 

 embryology of Lvmhricus^ a figure is also given of the cocoon 

 of Enchytnpus (/alba — it is evidently from the same drawing 

 as that which furnislied the figure already referred to. The 

 cocoon and contents are thus (on p. 49) described : — " II n'y 

 en a jamais qu'un seul [oeuf] dans une capsule; celle-ci est 

 sensiblement spherique et enveloppe completement I'oeuf; 

 seulement il y a deux points opposes oil on rencontre une 

 legfere ])rotuberance." 



With these illustrations and descriptions before him one 

 could not be blamed for regarding the structures figured by 

 ]\Iaggi as cocoons, from the drawings of which the " protu- 

 berances " had been omitted, since their slight development 

 rendered them inconspicuous, and therefore easily passed over. 

 The only difficulty in the way of making this comparison 

 would be the increase of size in the cocoon — a fact not readily 

 intelligible on the hypotliesis of its being a cocoon. 



In every drop of water which I examined from the source 

 aheady mentioned there were not only specimens of jEoIo- 

 soma Ehrenhergii crawling about, but very numerous round 

 capsules, containing what looked at first like developing 

 embryos of yEoIosoma. 



These capsules seemed to be occasionally attached to frag- 

 ments of weeds &c. ; but I fancy that they were merely lying 

 upon these bodies, and had no real connexion with them. In 

 any case there was no observable means of attachment, and 

 they were as commonly found lying freely in the water at 

 the bottom of the vessel in which they were placed. 



Each capsule contained a single jEolosoma, which appeared 

 to be always bent once upon itself, the tail lying close to 

 the head. The capsnles were nearly invariably i:>erfectly 

 spherical, but sometimes more irregular in form or oval ; 

 otherwise they recall Maggi's figure (fig. 11, f), where the 

 " embryo " is represented as being coiled in a position very 

 similar to that which I found. These capsules are quite 

 visible to the naked eye, their average size being about that 

 of Volvox ghhator. They are in every case perfectly motion- 

 less — that is to say, there was no motion of translation ; the 

 worms inside were, however, in active movement — not 

 crawling about within the cysts, but showing active contrac- 

 tions of the body and movement of the alimentary canal, the 



* '• D^veloppement du Lombric terrestre," M^ni. cour. et Mem. d. sav., 

 etc., Acad. Roy. Belg. t. xxrii. 



