364 Mr. Hogg's Observations on the Spongilla fluviatilis. 



and principally by examining its manner of growth from its small seedlike 

 body, and by comparing it with the similar origin and increase of certain Cryp- 

 togamic vegetables from their seeds or sporules ; and by contrasting it with the 

 mode of formation of some of the lower animals from their minute eggs or 

 ovules, some fact very probably may be elicited which is found to take place 

 only in the one division of nature, and not in the other, and thereby enable him 

 to determine with accuracy to which it ought really to be referred. 



These seedlike bodies on being magnified so exactly resemble true seeds, that 

 it is difficult to imagine that they can be the germs or ovules (ovula) of ani- 

 mals : in shape they are like small Pomegranates, or still more so, the seeds of 

 the South American Quinoa (Chenopodium Quinod). But they must be steeped 

 a little while in water before they are placed under the microscope, in order 

 to raise their tops or upper portions, which, resembling small dimples, by de- 

 siccation contract or become somewhat drawn in. 



The seedlike bodies, sporidia, or sporules, if the Spongilla be a vegetable, or 

 small ova, or ovules, if an animal, which are so numerous in the largest speci- 

 men 1 have the pleasure of presenting this evening, resemble a good deal those 

 belonging to the Lake Sponge* {Spongilla lacustris), and which are figured in 

 Esper's work on Plant-Animals — " Pflanzenthiere," vol. ii. Spang, tab. 23, A. 



Linnaeus in his " Flora Suecica," classed the Freshwater Sponges with the 

 Algae, and thus writes of the small bodies in the Spongilla fluviatilis : " Se- 

 mina lentiformia, in omni hujus poro, autumno conspiciuntur." (Vide p. 440. 

 edit. 2. 1755.). 



Oken in his "Lehrbuch der Naturgeschichte," vol. iii. Zool. Abth. 1. Jena, 

 1815, under the description of this kind of Spongilla, which he names Tupha, 

 observes, " This must be the habitation of the Cristatella :" — " Soil das Gehaus 

 von Cristatella sein," p. 78. And again, at p. 54, in his account of the Cris- 

 tatellce, he further adds, " The Freshwater Sponge must be their chosen re- 

 treat or cells, which is extremely probable. The grains that are found so 



* Professor H. F. Link in a very interesting memoir, wherein he says that the Sponges ought to 

 be separated from the Zoophytes and restored to the Alyte, has well described the seedlike bodies or 

 sporidia of the Spongilla lacustris. I was unfortunately not aware of its existence till long after my 

 letter was written. Vide " Annales des Sciences Naturelles, Seconde S6rie, torn. ii. Botaniqve." Paris, 

 1834, p. 328. 



