DIPLOSOMA CRENATUM. 411 



positively as to what these concrementa really are. Throughout, 

 indeed, it has been much more easy to state what they are not, 

 than what they are. Helminthological science is much indebted 

 to Schneider for his discovery of the true nature of the so-called 

 S^iro;ptera hominis, and we are no less indebted to him for paving 

 the way to a right understanding of the concrementa lymphafica. 

 Dr. Farre's minute microscopic details, also, by their negative evi- 

 dence, materially help one in arriving at a true estimate of their 

 character, although, unfortunately, they have led him to a diame- 

 trically opposite conclusion. For my own part (thanks, in some 

 measure, to the hints conveyed by Schneider's communica- 

 tion), I have arrived at a very definite opinion respecting these 

 examples of the so-called Diplosoma crenatum. I may be in error, 

 but I believe them to be carefully-cut slices of the ovisacs of 

 the cod and haddock; the so-called "lateral membranous flaps" 

 answering to the well-known ovarian laminse which are developed 

 in the peculiar ovisacs common to most osseous fishes. From 

 these laminge the piscine ova are ordinarily suspended in the early 

 stages of their development, but they are subsequently cast off by a 

 process of internal dehiscence, when they naturally, by their great 

 numbers, fill up the general cavity of the ovisac, constituting the 

 familiar hard roe. Ultimately they become the free, evacuated 

 spawn. Thus the ingenious patient, in the present case (troubled 

 with Diplosoma crenatum^ Spiroptera Jiominis, Concrementa lym- 

 phatica, and what not !) had, I believe, succeeded in puzzling 

 her medical attendant, and others, by resorting to the expedient 

 of cutting up the ovarium of a haddock, and inserting portions 

 thereof, along with the entozoa of the fish, into her urethra ! 

 Certainly, it requires a tolerably minute acquaintance with natural 

 history and comparative anatomy, to enable one to fathom the 

 mysterious habits of individuals who, for the purposes of decep- 

 tion, or otherwise, can thrust into their bladders such strange 

 kinds of pseudelminths. 



