114 REPORT 1864. 



5. Disfoma liepaticum. — On the 6th of Januaiy, 1863, numerous eggs 

 from the uterine tubes of one dozen flukes were placed in a jar of fresh 

 water containiag living vegetable matter (Anacharis). An examination of 

 the contents of the glass, on the 16th of March, revealed the presence of 

 many empty egg-sheUs, and others with immature embryos in their interior. 

 On the 13th AprU following, aU the embryos had apparently escaped ; but 

 they were not found in the water. Possibly they had been devoured by 

 Entomostraca. 



On the 6th January, 1863, a quantity of flukes' eggs were administered 

 to a frog ; but a subsequent examination of the reptile, after death, only gave 

 a negative result. 



6. Ascaris osculata.— On the 11th October, 1862, sections of two female 

 nematodes, taken from a seal, were given to a dog. The seal had recently 

 died, its stomach containiag upwards of 200 ascarides. 'None of the eggs in 

 these worms contaiaed embryos ; but the yelk was undergoing segmentation. 

 Subsequently, eggs of this parasite, containing embryos, were also given to 

 the same dog, and likewise, at a stUl later date, several free embryos. On 

 destroying the dog, November 28, 1862, no young nematodes could be 

 detected in its intestines. 



On the 31st October, 1862, numerous eggs containing embryos were given 

 to a dace (Lei(ciscvs rutUus) and to a goldfish (^Cyprinus anratus). On the 

 3rd November following, the dace was killed, without my finding any trace 

 of the ova ; but on the day following (Nov. 4) I destroyed the gold-carp, 

 and found in its intestinal canal numerous empty egg-shells of Ascaris 

 osculata. In the large tank, however, I sought in vain for these minute 

 embryos. 



On the 29th October, and on the 4th November, 1862, many eggs con- 

 taining embryos were administered to frogs. Two of these Batrachians were 

 subsequently examined (Nov. 10), without my finding either ova or embiyos 

 in their interior; but the water of the large glass vase which had imprisoned 

 the frogs was found to contain a number of empty egg-shells of Ascaris 

 osculata, as weU as numerous living embryos, apparently referable to 

 these ova. 



On the 4th November, 1862, eggs with embryos were given to several 

 freshwater fishes (gudgeon, carp, and dace) ; but the subsequent destruction 

 and examination of some of these fishes only yielded a negative result. 



On April 13th, 1863, several free embryos of A. osculata were adminis- 

 tered to a dog, which was after^vards destroyed on the 3rd of June. No 

 young ascarides, however, could be detected. 



On the 11th October, 1862, when I first procured the adult ascarides from 

 the seal, some of the ova were placed in a glass jar of fresh water containing 

 Chara, others in jars of salt water supplied with Zostera. On the 15th of 

 the same month, none of the ova appeared to have undergone any material 

 change. On the 29th (18 days) the majority of those placed in the fresh 

 water had developed into embryos within theii' shells, and not a few had 

 escaped free into the water. At the same date, however, the eggs placed 

 LU the salt water had made comparatively little progress. Their yelk-seg- 

 mentation had certainly advanced ; but no embryos could be seen. One 

 sohtary empty shell was found in the salt water ; but this may have resulted 

 from injury. On the 7th November, some of the free embryos in the fresh 

 water were found to display signs of growth, and one of them showed a 

 tolerably well-developed digestive apparatus. On the 2nd of the following 

 December, a largo number of the embryos in the fresh water had either 



