E. MARSHALLI. — TRABECULE. 157 



the possibility and perhaps the probability of its absence on the 

 thinner ones is thus admitted by him. Such a partiality, if true, 

 must be said at least to indicate a very remarkable case for an 

 epithelium ; whereas, if we had to do wàth cells of mesenchymal 

 nature, there would be nothing extraordinary in finding these 

 attached only to such thicker beams as are capable of bearing 

 them on. 



Secondly ; nuclei without the ' Knollen ' around them, and 

 which are numerously found, apparently situated in the connective- 

 tissue substance of the trabecular threads and membranes. These 

 nuclei are said to be on the average somewhat larger and of a more 

 oval form than those of the cells with the ' Knollen,' though in some 

 parts of the trabecular system there are present a number of such as 

 are indistinguishable from the latter nuclei in point of size or 

 of other features. In view of this agreement sliowai by the 

 relatively smaller nuclei under consideration, Schulze ('99a, p. 208) 

 leaves open the possibility, if I understand him aright, that these 

 smaller nuclei may belong to flat epithelial cells w^hich have not 

 accumulated the * Knollen ' in their bodies. The relatively larger 

 ones are at any rate regarded as the connective-tissue nuclei. 

 No special protoplasmic space around them seems to have been 

 seen, for no mention of it is made. These nuclei are said to be 

 the only kind that are found in the thinner trabeculœ and 

 especially in those spanning the spaces between the chambers ; so 

 that, to follow the writer's expression as nearly as possible, * here at 

 least ' the existence of an epithelial covering could not be ascer- 

 tained {I.e. J p. 209). However, he expressly leaves undecided 

 (19'a, p. 98) whether or not the diÔerence in size of the nuclei 

 ' alone and in all cases suflices for the distinction of the two kinds 

 of cells ' (i.e., flat epithelial cells and connective-tissue cells). 



