424 RECORD OF CURRENT RESEARCHES RELATING TO 



that a male of that genus has at last been found, is fully borne out by 

 its entire agreement with the typical forms already known. 



Structure and Functions of the Crustacean Liver.* — In the 

 discussion of this difficult question Dr. Max Weber commences with 

 an account of the liver of the Isopoda ; the glands in question are 

 tubular, and they pour out their secretion into the commencement of 

 the midgut ; the separate glands are, from within outwards, provided 

 with three coats : a tunica propria, a retiform muscular tunic in which 

 circular fibres are very well developed, and a tunica serosa, which 

 owes its origin to the fatty body. The secretion from these glandular 

 tubes has peptic properties ; but it does not follow that it is derived 

 from the true hepatic cells, for there are, in addition to these, other 

 cells which the author speaks of as ferment cells. The fatty nature 

 of the former, together with the fact that the secretion is not extracted 

 from the cells by water or by glycerine, but by ether, is altogether 

 against them. On the other hand, the method of exclusion is not the 

 only one which leads us to regard the ferment cells as the authors of 

 the digestive secretion. There are such positive facts as these : they 

 are rapidly and intensely blackened by osmic acid, while the so-called 

 liver cells, just like fat and bile, are indifferent to this reagent ; the 

 granules of the ferment cells of the Isopoda are very similar to those 

 of the salivary cells of the Vertebrata, which likewise readily blacken 

 with osmic acid. The so-called liver, or midgut gland, as the 

 author objectively calls it, has, then, two functions ; one of these is 

 comparable to part of the hepatic activity of the liver of the Vertebrata, 

 the formation, that is, of animal colouring matters ; the other is com- 

 parable to that of the digestive glands of the Vertebrate intestine, the 

 formation of a digestive ferment. To avoid confusion, the author 

 suggests the term of " hepato-pancreas " for the gland now under 

 examination. 



Passing on to the Amphipoda, we find that with some resemblances 

 there are certain difi"erences ; the cells of the " liver " are much 

 smaller, and the muscular reticulum, though not stronger, is more 

 close ; the nuclei are almost always found dividing at the blind end 

 of the tubes only. In the Decapoda we find a higher grade of 

 development; each glandular tube is surrounded by a well-differ- 

 entiated membrane of connective tissue, is separated from the sur- 

 rounding organs, and the active cells of the glands are more 

 numerous. As with the Isoi)oda, the secretions of the so-called 

 hepatic glands of the Amphipoda and Decapoda have a digestive action 

 on albuminous compounds, and as in them there is a secretion 

 comparable to bile. In addition to the two sets of cells already 

 distinguished in the Isopoda, it is possible in the two other sets of 

 forms to make out a third series, which produce a clear secretion in 

 the form of a large vesicle ; but this is not totally distinct from the 

 other two, but only a kind of predecessor to them. Although the 

 organ is called the " hepato-pancreas," it must not be supposed that 

 it is homologous with the two structures in the higher animals, 



* ' Avch. Mikr. Anat.,' xvii. (1880) p. 385. 



