12 RESEARCHES IN HELMINTHOLOGV AND PARASITOLOGY. 



boscis large and oblong ; eyes two, anterior, distant, each consisting 

 of two round masses of pigmentum nigrum in contact with each 

 other, and of which one is longer than the other ; generative orifice 

 one-fourth the length of the body from the posterior extremity. 

 Length i line. A single specimen found with the preceding ; but 

 probabh' not rare, for, from its small size, it escaped my notice while 

 collecting some of the former, and it was not until I got home that I 

 detected its existence in the vessel of water containing the others. 



The anatomy of P. macnlata does not differ from that of Planaria 

 ladea as given by Duges in the Annales des Sciences Naturelles. In 

 Pfostoma marginatum the digestive cavity has not the dendritic ar- 

 rangement of Planaria, but merely consists of a large capacious sac 

 extending as far back as the posterior third of the body, and having 

 a coecum upon each side of the proboscis. The penis has a yellow 

 colour and consists of a round granular mass, with a moderately 

 long and bent spiculum projecting from its posterior part. The 

 arrangement of the female apparatus I failed to trace. 



[October, 1849. No. 40 44. See Bibliography.] 



From the opinion so frequently expressed that contagious diseases 

 and some others might have their origin and reproductive charac- 

 ter through the agenc}^ of cryptogamic spores, which, from their 

 minuteness and lightness, are so easily conveyed from place to place 

 through the atmosphere, b}' means of the gentlest zephyr, or even 

 the evaporation continually taking place from the earth's surface ; 

 and from the numerous facts alreadj^ presented of the presence of 

 cryptogamic vegetation in many cutaneous diseases and upon other 

 diseased surfaces, I was led to reflect upon the possibility of plants 

 of this description existing in healthy animals, as a natural condi- 

 tion ; or at least apparently so, as in the case of entozoa. Upon con- 

 sidering that the conditions essential to vegetable growth were the 

 same as those indispensable to animal life, I felt convinced that 

 entophyta would be found in healthy living animals, as well, and 

 probably as frequently, as entozoa. The constant presence of myco- 

 dermatoid filaments growing upon the human teeth, the teeth of the 

 ox, sheep, pig, etc., favored this idea, and accordingly I instituted 

 a course of investigation, which led to the discovery of several well 

 characterized forms of vegetable growth, of which, at present, I will 

 give but a short description, for the purpo.se of establishing priority, 

 and propo.se giving a more detailed account of them, with figures, 

 in the second volume of the Journal. 



