262 FRANK E. BEDDARD. 
Die Zellen, aus denen diese Korper hestehen, sind grob granulirt 
und erhalten durch Einlagerung zahlreicher, schwarzer Korner 
ein Chloragogenzellen-artiger Aussehen. Ein starkes Blut- 
gefass geht mitten hindurch. Ich glaube erkannt zu haben, 
dass diese Korper mit den Segmentalorganen zusammenhan- 
gen, deren in je einem Segment ein Paar vorhanden ist. Es 
musste unentschieden bleiden, ob sie durch die ganze Lan ge 
des Ko6rpers oder nur am Vorderkorper ausgebildet sind. 
Soweit ich das Tier untersuchte, bis zum 20. Segment, sind 
sie vorhanden.” It seems to be possible that the structures 
which Michaelsen here describes (without any figures) are the 
same as the organs regarded by myself as the metamorphosed 
equivalents of the calciferous glands of other Eudrilids. The 
account of the minute anatomy which Michaelsen gives, 
though not very full, agrees so far as it goes with the organs 
in question. They have a kind of resemblance to a fat body, 
and the cells of which they are composed are distinctly ‘‘ grob 
granulirt,” but they do not, so far as my own observations go, 
contain any black pigment. Another difficulty, and the most 
serious one in the way of comparing the glands of Megacheta 
with those of Stuhlmannia, &c., is the fact that in the former 
genus they extend back as far as the 20th segment. This is 
too far, one would be inclined to suppose, for glands to extend 
which are homologous with calciferous glands, connected as 
they are in all earthworms with the esophagus. The close 
proximity of the nephridia to the glands might easily give the 
impression that the two series of organs were connected. The 
fact that they are traversed by a strong blood-vessel is another 
point of resemblance to the calciferous gland of Stuhl- 
mannia, &c. 
§ Note on the Substitution of Organs as Illustrated 
by the Spermatothece in the Eudrilide. 
I do not think that attention has been directed to the ex- 
cellent instance which the spermatothece of the Eudrilide 
afford of the substitution of one organ for another (physio- 
