410 Miscellaneous. 



saccule, which opens directly into the vesical system *. The vesical 

 system is constructed approximately upon the same plan as in 

 Crangoiif ; there is no unpaired sub-stomachal bladder, but two 

 sub-stomachal lobes, much closer together than in Crangon ; this 

 approximation appears to mark a transition towards the unpaired 

 sub-stomachal bladder of Pcdcemon. There is a wide communication 

 between the two vesical systems by means of a broad commissure, 

 situated in front of the stomach, and prolonged beneath this organ 

 by means of a median and unpaired mass which plunges into the 

 labrum ; we find a rich vesical collar surrounding the a-sophagus. 



Alphevs {A. ruber) exhibits a vesical system resembling that of 

 the Crangonids. We meet with two sac-shaped lobes, descending 

 along the sides of the stomach ; on each side of the oesophagus there 

 is detached a long narrow lobe, which extends as far as the base of 

 the first pair of limbs. 



In Caridina Desmarestli, a fresh-water type, the gland presents a 

 saccule and a labyrinth. As in Falcemon, the saccule forms a little 

 rounded mass, distinct from the labyrinth, partitioned in its interior, 

 and projecting into the interior of the bladder : it communicates 

 with the lacunse of the labyrinth by means of a kind of atrium. 

 The gland is capped on its inner face by a sac which represents the 

 bladder : the latter is of small size, and presents the peculiarity of 

 being continuous with a broad canal of which it is only the expan- 

 sion ; this canal winds somewhat, and opens, narrowing at the same 

 time, at the level of the excretory tubercle. 



II. The production of the urinary liqiiid in Crustacea is not due 

 to a simple filtration, as the limpidity and abundance of the liquid 

 which fills the bladder might lead us to believe ; there is a real 

 secretion, with separation of the cellular portions. In the liquid 

 excreted by Main, we find perfectly round and refringent globules 

 of variable size ; the same is the case for the Crayfish, the Spiny 

 Lobster, &c. 



In the Pcujuri, the clear liquid which inflates the abdominal 

 bladder contains vesicles, which are more or less granular, often of 

 large size, and may enclose a larger or smaller number of secondary 

 vesicles. When the animal has been injected with indigo-carmine, 

 we find blue granulations in these vesicles. 



If we examine the bladder in the urine or the blood of the 

 animal, we find that the cells are swollen so as to form domes, or 

 large transparent vesicles, often enclosing secondary vesicles. On 

 being set at liberty, they constitute the vesicles which we find in 

 the excreted liquid ; when they are free, their membrane has a very 

 low degree of resistance : one drop of picro-carraine is enough to 

 cause them to disappear in a few moments. 



I have found the same swollen vesiculated cells in the bladder of 

 the most varied types : it is evident that the bladder takes an 

 important part in the secretion. 



* AVeUlon has just determined the same fiict in Crangon, and my 

 independent researches on the same animal have confirmed this result. 



t I described the bladder of Crangon in n previous note (' Comptes 

 Reudus,' October 20, 1890). 



