ON THE BLACK PULP LEECH. 



245 



(bronchii,) that there can be any more possibility of revivifying them 

 after death than any other animal to which respiration is an essential 

 condition of life. Yet upon the faith of observations inaccurately made 

 and inaccurately repeated, it has been promulgated for an age that the 

 wheel animalcules, when long deprived of water, and remaining as if 

 dead at the bottom of the places where they are preserved, revive as soon 

 as they are moistened. There is no possible means which I have not tried 

 to arrive at such a result ; but I have never succeeded. I have some- 

 times, upon moistening the tubes of caddis worms, (Phryganece,) 

 after long desiccation, or putting some water into vases filled with 

 sediments of animalcules, which had been a long time amassing in my 

 window, refound some wheel animalcules, but not resuscitated : they 

 were only evolved like the Daphnice, and other Entomosfraca, whose 

 eggs (ovules) remaining in the soil, are hatched when the rain supplies 

 the fluid necessary for their evolution. For twenty years I have 

 repeated this statement ; but it requires reiteration, because those who 

 write on the microscope, copy the works of Spallanzani, contained in 

 almost every library, whence we find passages literally transcribed in 

 compiled books, unfortunately at present too much diffused. 



ON THE BLACK PULP LEECH (Planaria nigra, Muller). 



BY J. G. DALZELL, ESQ. ADVOCATE, F. S. A., EDINBURGH*. 



During the sunshine of summer, a small jet black velvet- skinned 

 animal may be often seen crawling near the edge of fresh water ponds 

 and ditches, with a lively, smooth, and gliding motion. This is the 

 Black Pulp Leech, (Planaria nigra,) which has been already charac- 

 terised and described by different naturalists ; but, unfortunately for 



* From " Observations on the Planarife." Mr. Dalzell is understood to have 

 a splendid work in preparation, comprehending these singular animals. 



