376 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of certain Crustacea. Within tlie cells there are spheres or drops, 

 which vary in size and number, but almost always occupy nearly the 

 whole of the cell ; they are generally, though not always colourless, 

 and their exact chemical composition has not been definitely made 

 out, though they present in some cases the reactions of fatty bodies. 



Between these cells lie others, the number of which varies consi- 

 derably, but is always in direct relation to the nutritive condition of 

 the individual. They present the same fringe and longitudinal 

 striation as the fat- cells ; the greater part of each is filled by the true 

 secretion-bodies which are almost completely spherical, surrounded 

 by a delicate membrane, and containing crystals which appear to be 

 formed of tyrosin. When the ferment-cells are set free the vesicles 

 and their contents make their way into the stomach and intestines. 

 If the animal is in a normal condition the contents are gradually 

 extracted and dissolved; but if the nutrition or digestion is in 

 a disturbed condition, as is often the case with animals in confinement, 

 then the ferment-vesicles pass almost unchanged from the intestine 

 with the faeces. 



The organ of the mid-gut cannot rightly be called a liver, for it 

 has not that which is the prime characteristic of a liver — colouring 

 matters, nor can bile-acids or bile-colouring matters be detected in 

 its secretions. It is possible that the fatty cells also contain a fer- 

 ment, but the presence of it has not as yet been definitely proved. 



'Challenger' Copepoda.* — G. S. Brady's report on the 'Challenger' 

 Copepoda has just appeared; it contains a description of 43 new 

 species and 11 new genera. One of the latter, Pontostratiotes, 

 which contains but a single species ahyssicola, is an undoubted deep- 

 sea form, having been dredged in a depth of 2200 fathoms ; it is 

 characterized by an unusual development of spines upon the carapace 

 and anterior antennae ; it is possible that a certain number of other 

 forms, Calanus princeps, Hemicalanus aculeatus, PJiyllopus hidentatus, 

 which came up in the dredge from great depths, are also abyssal, but 

 in these cases it is not positively certain that the specimens really 

 came from the bottom. The other Copepoda were all taken in the 

 surface net at the actual surface and at various depths below. Like 

 most other pelagic organisms, the genera and even the species are 

 very widely distributed. An accurate analysis of the localities in 

 which all the species were obtained is given, and the geographical 

 areas into which the ocean is divided are the same as those used in 

 the report on the Ostracoda, viz. North Atlantic, South Atlantic, 

 South Indian Ocean, Australasia, South Pacific, North Pacific, East 

 Asia. Of the 90 free-swimming species here tabulated, only one 

 (Enchceta prestandrece) was found in all the seven districts, but no 

 fewer than nine species occurred in all but one of the areas. The 

 area producing the smallest number of species (15) is the South 

 Indian Ocean; from the North Pacific the number is not much 

 greater, 22. Leaving out of consideration the fish parasites, which 



* 'Keport, &c., H.M.S. Challenger,' Zoology, xxiii. (1883) 4to, 142 pp. 

 (55 pis.). 



