EOHINOEHYNCHUS. 101 



Development. — Until very recently we were totally ignorant of 

 the changes undergone by the larval Bchinorliynclii from their 

 earhest embryonic condition up to the adult state, and what we now 

 know is entirely due to the researches and discoveries of Leuckart. 

 Some few years back, indeed, Dr. Gruido Wagener* furnished us with 

 a series of admirable illustrations of the full-grown eggs and embryos 

 of several species of Echinorhynchus, but from the facts then elicited 

 he was erroneously led to conclude that the larvae passed through 

 their entire course of development in a simple and direct manner. 

 He even conjecturally indicated the presence of lemnisci and digestive 

 organs lodged within the parenchymatous substance of the bodies 

 of the larvae ; the surfaces of the latter being armed throughout with 

 minute, closely-set, and sharply-pointed cutaneous spines. These 

 results were obtained from Echinorhynchus polymorphus and E. 

 filicollis, and they seemed to confirm the somewhat similar views 

 previously held by Siebold and Dujardin. The notion of a simple 

 metamorphosis, however, has been entirely disproved by Leuckart, f 

 who finds the growth and development of the young to be brought 

 about by the phenomenon of a true alternate generation. This, at 

 least, is the case with Echinorhynchus proteus, a species abimdant 

 in the Trout and many other fresh- water fishes. The embryo in 

 this last-named species is broad and obhquely truncated at the 

 ventral surface anteriorly, being gradually narrowed to a blunt 

 point posteriorly, and at the front part, on each side of the middle 

 hne, there are five or six spines biserially disposed. Similar 

 features are displayed by the embryo of Echinorhynchus filicollis. 

 The cortical layer of the body of the embryo of Echinorhynchus 

 proteus is made up of a thin cuticle succeeded by a firm dermis, 

 which invests a tolerably uniform mass of contractile parenchyma. 

 The centre of the embryo is occupied by an oval-shaped granular 

 mass, which is altogether free -and unconnected with the surrounding 

 contractile tissue. Its nature is not clearly made out, but Von Sie- 



* Siebold and K6lliker's " Zeitsohriffc," vol. ix., p. 73, ct seq. 

 f " Helminthologisbhe Bxperimentaluntersuchungen." Gofctingen Nachrichten. 1862. 



