ZOOLOGY AND BOTANY, MIOROSOOPY, ETC. 215 



Fossil Calcareous Elements of Alcyonaria and Holothurioida.* — 

 Herr P. Pocta has found in the calcareous strata of Bohemia not only 

 Foraminifera, Ostracoda, and calcareous spines and needles of unknown 

 origin, but calcareous elements which appear to come from a new species of 

 Alcyonarian which he calls Nephthya cretacea, and plates which closely 

 resemble those of Psolus phantajpus. 



MoUusca. 



Histology of the Mollusc Liver.f — In a long memoir Dr. J. Frenzel 

 reports the result of his investigation of the histology of the mid-gut gland 

 or liver of Mollusca. His researches include a considerable number of re- 

 presentative forms from all the sub-classes. After a full historical intro- 

 duction the author passes to the discussion of, 



1. TTie histology of the glandular epithelium, (a) The granular cells. — 

 Granular cells, the liver-cells of Barfurth, occur in all molluscs except 

 Cephalopods. They are most developed in the Opisthobranchiata. They 

 contain, besides protoplasm and nucleus, a distinct spherical vesicular ball, 

 inclosing more or less markedly pigmented granules, fat-globules of various 

 size, and albumen-clumps in variable abundance. The pigmented granules 

 are constant, the others may be absent especially in ripe cells. The fat 

 varies with external conditions, and the same may be said of the occurrence of 

 crystals. The size, shape, and contents of the cells are discussed in great 

 detail, as also the results of various reagents. The presence of a hair-fringe 

 is noted, which in Cephalopoda and some Lamellibranchs is long and in 

 the latter occasionally mobile. From this the author maintains a ciliated 

 fringe might be derived. 



(&) The club-shaped cells, or ferment-cells of Barfurth, vary very greatly 

 in form and contents. All the different forms are regarded by Frenzel as 

 modifications. They seem to occur in all types of molluscs. As in the 

 granular cells, they contain a secretion-ball, also with more or less pigmented 

 contents, which are however fluid, or at most drop-like. Fat and albumen 

 clumps, and in one case a crystal, are again present. The size, form, 

 contents, changes, and reactions of the cells are noted at great length. 

 The secretion occurs in fluid drop- like form, in clumps, or in firm spheres, 

 The secretion of the granular cells withstands strong acids which dissolve 

 that of the clubbed cells, but the difference is really only quantitative. 

 Herr Frenzel comes to no definite conclusion as to the origin of the club- 

 shaped cells. 



(c) The lime-cells. — There is a frequent, but by no means general occur- 

 rence of cells with strongly refracting spheres of calcium phosphate. The 

 following chapter of the memoir discusses the actual occurrence of these 

 three elements in specific forms. 



2. The physiology of the liver. — Dr. Frenzel regards it as demonstrated 

 that the mid-gut gland of all molluscs has a digestive function, and that 

 this function is discharged both by the granular and club-shaped cells, 

 while the lime-cells are certainly not secretory. The pigmented contents 

 form the principal portion of the digestive ferment. No proper bile contents 

 could be demonstrated. Frenzel regards it as premature to ascribe to the 

 organ any other function than that of secreting a digestive ferment, though 

 the complex and variable histology may suggest something more. The 

 memoir is accompanied with a gorgeous coloured plate. 



* SB. K. Akad. Wiss. Wien, xcii. (1885) pp. 7-12 (1 pi.). 



t Nova Acta Leop. Carol. Acad., xlviii. (1886) pp. 81-296 (3 pis.). 



