ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 49 



agree generally with the account given by Schwarze of Distomum enclo- 

 bolum, but they are confident that the spermatozoa arise wholly from 

 the nuclei of the sphere or spermatogemma. They have been able to 

 observe the passage, under pressure, of the female sexual products to the 

 intestine through the overflow-tube, and regard this as a confirmation of 

 Ijima's discovery of the true nature of the so-called internal vas deferens 

 of Polystomum. Some details are given as to the minute structure of the 

 female organs; in Ihe ovary there are parietal cells, varying considerably 

 in size, and from them arise, by increase in size and division, the cells 

 which fill the cavity of the ovary ; the ripe ova measure about 55-60 /*, 

 and their nuclei about 35-40 /x. The uterus never contains more than 

 one egg, and the extent of development of this seems to stand midway 

 between the advanced condition found in Polystomum oblongum and P. 

 ocellatum, and the early oviposition which occurs in P. integerrimum. 



New Human Distomum.* — M. J. Poirier describes, under the name 

 of Distomum rathouisi, a new species of fluke obtained through Pere 

 'Eathouis, and taken from a Chinaman thirty-five years of age. As the 

 patient suffered for a long time from hepatic derangements, which were 

 refractory to all remedies, it is probable that this new endoparasite 

 inhabits the biliary canals. In a number of characters it resembles 

 D. hepaticum, but is distinguished from it by the large size— 2 mm. in 

 diameter — of the ventral sucker, by the absence of spinous processes 

 from ihe integument, and by the absence of ramified caeca connected 

 with the two branches of the intestine, as well as by the smaller size of 

 the elements of its parenchyma, and by the structure of its uterus. 



Natural History of Leucochloridium paradoxum.f — Herr G. Heckert 

 has found that Leucochloridium paradoxum is not rare near Leipzig. It 

 is, as is well known, the sporocyst stage of Distomum macrostomum, and 

 is found in the liver of the snail, where it forms a network of multi- 

 ramified tubes which are filled with a serous fluid, germ-spheres, and 

 the larva? developed from them. Parts extend into the tentacles, and 

 thither the ripe forms make their way. Both the sporocysts and tubes 

 are subject to a very high pressure, and if they are injured their contents 

 are rapidly expelled. Even the young tubes exhibit contractions, which 

 are probably of importance in metastasis ; the large tubes not only effect 

 this, but with their colour attract birds, who regard them as living 

 larvae ; their musculature is very well developed, consisting of longi- 

 tudinal, circular, and diagonal muscles. Below the dermo-muscular 

 layer bright green pigment is found in cells, which are arranged 

 circularly. The brown tubes sometimes seen probably belong to different 

 sporocysts. The sporocyst and tubes are of the same histological 

 structure ; there is an external cuticle, a dermo-muscular tube, then a 

 layer of cells which varies in size with the stage of growth, and finally 

 a membrane with distinct cellular elements. In this last the germ- 

 spheres arise as local thickenings, which, when they fall off, pass into the 

 nutrient fluid which fills the sporocyst ; they are chiefly made up of 

 small cells with proportionately large nuclei, and only in the centre are 

 there some larger cells. The spheres have at first the form of a lens 

 which gradually becomes oval ; the genital apparatus is developed from 



* Arch Zool. Expe'r. et Gen., v. (1887) pp. 203-12 (1 pi.). 

 t Zool. Anzeig., x. (1887) pp. 456-61. 

 1888. E 



