534 E. A. MINCHIN. 



In the following year (1865) were published Lieberkiihn's 

 observations upon "Grantia botryoides" = Leucoso- 

 lenia Lieberkiihnii, O. S., of which it is not too much 

 to say that his descriptions attain a far higher degree of 

 truth and correctness in many points than some which have 

 appeared more than a quarter of a century later. He recog- 

 nises at the outset the fact of the body-wall being composed 

 of two distinct layers, "a layer of contractile parenchyma 

 and a layer of ciliated cells which clothe the inner surface ^' 

 (p. 734). Here we have the two layers for which I have 

 revived HaeckeFs terms, dermal and gastral layer; in the 

 former "spherical, oval, and stellate corpuscles, at varying 

 distances from one another, can be distinguished in the trans- 

 parent homogeneous parenchyma " (p. 735). On the same 

 page we are told that just below the oscular margin the ciliated 

 lining ceases, and the aperture is surrounded by a simple layer 

 of jelly substance ; what better description could be given of the 

 oscular rim, of which it has so strangely fallen to my lot to main- 

 tain the existence and to point out the significance? Further 

 on (p. 738) the author repeats the observation, and gives it a 

 more general application ; and on p. 742 he shows that a 

 similar region occurs in Sycons. With regard to the spicules 

 Lieberkiihn observes (p. 736) that on many of the projecting 

 gastral rays "a. fine layer of the contractile substance [i.e. of 

 the dermal layer] can be seen pushing its way out between 

 the ciliated cells, and either covering the spicule completely 

 or partially in a fine layer, or enclosing only the root of 

 it in a thicker mass (Anhaufung)." Treatment with acetic acid 

 dissolves the spicule, " and the contractile substance remains 

 behind as a more or less thin-walled sheath." Hereby the 

 author thinks that Kolliker^s observations^ which he quotes, 

 receive an explanation ; and he further observes, " In favor- 

 able cases the conical mass can even be traced through the 

 epithelium, and recognised in continuity with the contractile 

 substance, in many places very granular. Besides this, the 

 same forms of thickened sheaths of the contractile substance 

 can be found singly on the free outer surface [doubtless the 



