61$ SUMMARY OF CURRENT RESEARCHES RELATING TO 



infected by the parasite, in spite of precautions which made it seem 

 impossible that the infection could have taken place per os. He noticed 

 next that if a drop of water containing living larvae was by chance 

 spilt upon the skin, e.g. between two fingers, there resulted a burning 

 sensation, and a noticeable reddening of the surface. Microscopic ex- 

 amination showed the presence on the affected surface of some dried or 

 shrunken larvae, but also of numerous cast coats of larvae. The next 

 experiment was to place a drop of larvae-containing water on the skin 

 of a patient about to undergo amputation of a limb. This was done 

 on a carefully cleaned area of the sldn, about an hour before the time 

 fixed for the operation. Immediately after the operation, the area of 

 skin treated was removed from the severed limb, fixed, hardened, and 

 ultimately sectioned. It showed some larvae in the act of penetration, 

 and other very numerous specimens which had completely penetrated 

 the skin, and lay in the hair-follicles. In all cases entrance took place 

 through the chink between the hairs and their follicles, the follicles 

 sometimes containing numerous larvae. The proof of the possibility of 

 cutaneous infection is thus decisive. The author is further of opinion 

 that it probably plays a much more important part in the life-history of 

 the parasite than infection with food or drink. The larvae do not float in 

 water, and could only be swallowed with sediment, while cutaneous in- 

 fection by means of contaminated mud helps to explain the frequency 

 of the parasite amongst Egyptian agriculturists, and the occurrence of 

 epidemics of it among brick-makers, railway navvies, and so on. 

 Washing the hands in 90 p.c. alcohol acted as a complete preventive to 

 infection. 



Platyhelminthes. 



Regeneration in Leptoplana atomata.* — E. Schultz has made ex- 

 periments on this Polyclad, which he cut across near the pharynx. No 

 regeneration of the anterior part occurred, but only of the posterior 

 half. The epithelium grows over the surface of the wound, the muscular 

 layer is retarded in its growth, and thus it comes about that during the 

 period of regeneration the epithelium and parenchyma are in direct con- 

 tact at the j>osterior end. After the restoration of gonads, &c, muscle- 

 cells begin to be insinuated beneath the epithelium. 



The nervous system is re-established wholly from ectoderm ; the 

 whole of the male copulatory apparatus is also of ectodermal origin, as 

 in ontogeny (Lang) ; the same is true of the uterus, which is also ecto- 

 dermal in ontogeny (Graff). The new gonads arise in the mesenchyme, 

 as in Triclads, not as diverticula from the gut as Lang described. On 

 the anterior end of the excised posterior part, the margins of the wound 

 close in in such a way that the median anterior point, from which re- 

 generation should especially proceed, comes to lie internally, shut off 

 from the outer world by parenchyma, muscular tissue, and ectoderm. 

 The author goes on from this to explain why the anterior end is not 

 regenerated. 



Revision of Species of Allocreadium Lss.f — Th. Odhner makes 

 a contribution to the systematisation of the chaotic genus Distomum by a 



* Zool. Auzeig., xxiv. (1901) pp. 527-9. 



t Zool. Jahrb., xiv. (1901) pp. 483-520 (ljpl.). 



