On the 17th of May, 1872, I communicated to the Metropolitan Counties Branch of the British Medical Association a paper on ‘_Bilharzia_,’ and in an Appendix to it I wrote as follows:--“A most interesting circumstance connected with this case of ‘_Bilharzia_’ from Natal lies in the fact that I obtained from the patient some other urinary parasites in the egg-condition (fig. 38). On five separate occasions I obtained one or more specimens of the eggs or embryos of a minute nematode. In one instance there were about fifty of these ova in the urine, their contained embryos being well developed and in a state of activity. Usually they were all in this advanced condition; but on the 25th of July, 1870, several were observed in much earlier stages of development. One of these was of a triangular form; its shape, granular contents, and clearly defined limiting membrane, indicating separation from the rachis within the ovarian tube. Another early form was perfectly spherical, with a well marked chorional envelope and double contour. These forms measured about 1/750″ in diameter. The fully grown eggs observed at the same time gave a longitudinal measurement of 1/500″ by 1/1000″ in breadth. On adding any stimulus, such as diluted sulphuric acid, the embryos moved themselves freely within the egg. After allowing the urine to stand for forty-eight hours, I found, on the 27th of July, that the shells of the ripe ova had dissolved, leaving the embryos dead, but still coiled within a fine transparent envelope. In this state they were easily separated and examined, when they gave a measurement of 1/300″ in length, by 1/3500″ in breadth. On two occasions, whilst engaged in rearing the larvæ of _Bilharzia_ in water, I noticed single specimens of these embryos lying dead; and one of the examples thus observed gave a length of 1/150″, by 1/3000″ in breadth.” [Illustration: FIG. 38.--Group of eggs and embryos in a case of endemic hæmaturia (1870). Original.]