MEMORANDA. 303 



developmental history of tlie Entozoa. It is far more prob- 

 able to suspect tliat the person had herself introduced the 

 worms into that situation. Instances of a similar kind, 

 with various articles, are common enough. The Filaria 

 piscium could be readily procured in London, and would be 

 well known to any one in the custom of eating fish. How 

 well known and abundant they are may be gathered from the 

 circumstance, that in Copenliagen the haddock is not eaten in 

 summer, owing to its containing too many of these parasites. 

 There is no reason, therefore, for surprise at the circumstance 

 that the patient in question, in the course of two years, passed 

 1,000 of these worms, and that the deception was carried on 

 for so long a time. 



A second bottle contains several slender shreds of matter, 

 about an inch in length, which have also been noticed by 

 Kudolphi, who describes them as " concrementa lymjjhatica." 

 Their structure and origin Dr. Schneider could not determine 

 with any certainty, but considers it not improbable that they 

 are portions of intestine cut fine. 



But if any doubt could be entertained as to a deception in 

 this case, none whatever can attach to the contents of the 

 third bottle. This contains round, tolerably firm, vesicular 

 bodies, which passed through the catheter when introduced 

 into the bladder. Mr. Barnett regarded these bodies as the 

 ova of the worm, and Rudolphi as " concrementa lymphatica." 

 But it is clear beyond all dispute that they are the ova of a 

 fish, of which they exhibit every distinctive character — the 

 facetted outer membrane covering the cells of the membrana 

 granulosa, beneath which is the shagreen-like coat, and lastly, 

 the vitellus, with its large oil-globules. 



Notes from Madras. — In an article^ that appeared in the 

 ' Bibliotheque Universelle de Geneve,^ written by Professor 

 Thury, a rule is given for finding the equivalent focal length 

 of a compound object-glass, which rule being freely trans- 

 lated may stand thus : 



To find the equivalent focal length of the compound objec- 

 tive, replace the ordinary negative eye-piece with a positive 

 eye-piece micrometer, the scale of which has a known value, 

 and place in the focus of the objective to be measured a stage 

 micrometer of the same value. 



Let N be the number of divisions of the eye-piece micro- 



* Notice sur les Microscopes. — ' Reniarques siir uu article du 'Journal de 

 Sillimann' relatif aux Microscopes de Spencer et a la structure des pores du 

 bois dans les Conileres, et considerations sur les Microscopes en general.' 

 Tar M. Ic Professeur Thury, No, xxxii, Aout/ISGO. 



