Miscellaneous. 317 



Xote of the Observation of Cilia in Grantia. By "William Mur- 

 ray DoBiE, M.D., Annual President of the Royal Medical Society 

 I of Edinburgh. 



The present somewhat dubious position of the Sponges in the 

 systems of naturalists, leads me to hope that the following isolated 

 observation may not be without its value, as an additional proof of 

 the distinctly animal nature of these organisms. 



At the end of last February, while residing for a short time at 

 Marshal meadows, near Berwick-on-Tweed, I had an opportunity of 

 examining perfectly fresh specimens of a species of Grantia, in which 

 very distinct and vigorous currents were in constant operation. 

 Having scraped a portion of the gelatinous covering from the interior 

 wall, and laid this on a piece of glass, and covered it with a thinner 

 piece, I viewed the specimen through an achromatic microscope, am- 

 plifying about 150 diameters. The field of view was crowded with 

 the minute granular cellules of the sponge, which, although they do 

 not always show a distinct nucleus, are, I have no doubt, of the same 

 nature as nucleated particles in general. These cellules •were in a 

 state of active and independent motion, and, when aggregated into 

 masses, very much resembled some of the Compound Monads. When 

 a single particle was seen isolated, the motion was of a jerking cha- 

 racter, suggesting at once the existence of cilia, if they could have 

 been seen. I now proceeded to a more accurate scrutiny. Another 

 specimen was selected ; a portion of the gelatine was diluted with 

 water pressed from the interior of the sponge, and the whole covered 

 with a film of glass of 1-1 20th of an inch in thickness. This I viewed 

 with a very excellent l-8th of an inch lens, by Smith and Beck, mag- 

 nifying 450 diameters. The size and apparent motion of the cellules 

 being thus greatly increased, I now could, without much difficulty, 

 detect extremely attenuated cilia attached to every particle in the 

 field of view, and lashing with considerable vigour. "When the light 

 and focus were adjusted with great care, I was able to sketch a con- 

 siderable number of the individual particles. The average length of 

 each cilium was equal to three times the diameter of the cellule to 

 _which it was attached. No perceptible difference in thickness could 

 ■be observed throughout its entire length. Each cellule very strongly 

 fcesembled some species of Monads. The motion ceased in all the 

 |*particles very soon after separation from the general mass. I was 

 mh\e to repeat this observation several times in the Grantia. In the 

 wBalichondria, which I found at the same time, no currents could be 

 ■seen. Only in one example could 1 find anything resembling ciliated 

 particles, and that very imperfectly. No further opportunity pre- 

 sented itself for continuing these observations. 



From this it seems evident, that in the Grantia the whole inner 

 surface is lined with a ciliated epithelium, and that the currents are 

 produced by the motion of these filaments. 



I have little doubt that cilia will eventually be found to exist in all 

 marine sponges, where currents are in operation, provided sufficient 



