THE MYXOSPOKIDIA, OR PSOROSPERMS OF FISHES. 95 



the great similarity between tlie spores and the pseudonavicellse. He 

 says: 



For the furtlier fate of our psorosperms it is not without interest to observe that 

 they frequently occur free in the bile passages, while on the contrary they are no 

 longer to be found in the intestinal canal, in which they, however, incontestably 

 arrive. May they not here develop directly into those round worms which we not 

 rarely encounter in the intestinal canal of these fishes. 



Charles Eobin was the first to assert their vegetable nature. In his 

 JBistoire Naturelle des Vcgetavx Parasites (Paris, 1853, pp. 291-2, 321), 

 he collected descriptions and figures of nearly all the previously 

 described species, placing them (as a special tribe, the Psoros;permece) 

 under the Diatoms. He says : 



Several facts have convinced me of the vegetable nature of these bodies. These 

 are the entirely peculiar aspect of the species' that I have had under observation; 

 the definite rupture of the coriaceous cells of which they are composed: the pres- 

 ence upon some of special opercles ; their contents partly homogeneous, partly 

 formed of drops of oil in suspension in a clear liquid; the solubility of the walls, 

 which often occurs in concentrated sulphuric acid in the manner of cellulose (although 

 they are not colored by iodine). Like Muller and Retzius * * * i believe that 

 these vegetables approximate by their form and general structure to the Diatoms, 

 among other forms to Nanicula and Melosira, etc., although they differ in the absence 

 of silica in the walls. * * * Like the Diatoms they can live either free or 

 reunited into colonies. * » * Although it is probable that the species described 

 below will one day form at least two genera, * * * j shall unite them provision- 

 ally [under one genus.] 



Lieberkiihn^ in his first paper expressed the opinion that the "pso- 

 rosperms " could not be, as Leydig supposed, Gregarines, inasmuch as 

 they possessed no nucleus. In his second paper ^ he again rejects 

 Ley dig's view in so far as the innominate form {Gen. incert. sp. 12) found 

 by him under the skin of Gasterosteus aculeatus is concerned, saying 

 that : 



This mode of origin [the process of spore formation] is so peculiar that we cer- 

 tainly can not reckon such formations among the Gregarines. Their size, absence 

 of structure, occurrence in water, the importance for reproduction of the granules, 

 and the observed young stages, all give rise to opinions but not to certain knowl- 

 edge. 



Further, it is doubtful, he says, whether any Gregarine lives in 

 water, whereas in all probability the psorosperm animal does, and 

 attaches itself to the skin merely for reproduction. That the " psoro- 

 sperms " are not amoebae is indicated by his failure, on careful inves- 

 tigation, to find any of them capable of taking up foreign bodies into 

 their substance. Also, he was never able to find an amoeba which had 

 just attached itself to the skin preliminary to reproduction. He con- 

 cludes by saying that his researches on the parasites of fresh-water 

 sponges promise to throw light on this subject, as he has there found 

 large psorospermiform bodies consisting of small and large globular 



^ Psorospermia sciasnw-itmbrce Robin (see p. 166). 

 * Miiller's Archiv., 1854, j). 5. 

 ^Jlid., pp. 357-367. 



