ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 749 



without spines move towards the light iu a very diflerent manner ; all 

 forward movemeut is spiral and so indirect, an I is frequently impeded 

 by somersaults, which appear to be involuntary ; after each of these the 

 zooea will hang for a moment vertically in the water, us if to recover its 

 sense of direction. 



Ccelom and Nephridia of Palaemon serratus.*— Mr. W. F. R. 

 Weldon commenced his investigations into the ccelom and nephridia of 

 Palsemon serratus by an attempt to repeat the experiments on secretion 

 recently described by Kowalevsky ; j the colouring matter is taken up 

 by the coelomic and nephridial cells. If a prawn so stained be dissected 

 in strong alcohol, it will be seen that a blue area in the thorax is 

 connected by a dee[)ly stained band of tissue with each nephridium ; the 

 blue area in the thorax is a sac which contains a clear fluid that is not 

 blood ; at its anterior extremity this sac gives off a pair of tubular 

 processes, one on each side, each of which jjasses downwards to open 

 into the urinary bladder of its own side. At its hinder end this sac is 

 in close contact with the gonad ; in other words, it is jirecisely similar 

 in all its relations to the coeloniic sac of a Mollusc. 



The long narrow tube which connects the ccelom and the nephridia 

 is beset with small cfeca, and, from about its middle point, gives off a 

 long branched tube, which ramifies am(mg the tissues of the base of the 

 eyestalk and of the first auteuufe. Similar tubules are given off from 

 tlje bladder. All thoje caecal appendages of the coelomic system are 

 liued throughout by an epithelium which is perfectly characteristic. 

 '1 he spaces found by Laukester in the limbs of Astacus are possibly 

 derived from processes of the nephridio-coelomic apparatus of the same 

 nature as those iu Palaemon. Mr. Weldon describes the structure* of the 

 nephi'idial apparatus, and points out that the comparison so often made 

 between the glomerulus of the vertebrate kidue}' and the end-sac of the 

 crustacean green-gland is abundantly justified, each glomerulus being the 

 termination of a ctecal outgrowth from a bent nephridial tube, which 

 cotumunicates on the one hand with the body-cavity, and on the other, 

 either directly or indirectly, with the exterior. 



Phosphorescent Infection of Talitrus and other Crustacea.^ — M. 

 A. (iiard reports that he observed at Wimereux a Talitrus which was 

 so phosphorescent that he could not accept the explanation of Quatrefages 

 that it was due to the presence of Noctibicse on the carapace. The 

 animal was, further, observed to be moving slowly. Microscopical 

 examination of an appendage showed that there were microbes in the 

 muscles, the structure of which had been considerably altered. Treated 

 with gentian-violet the microbe was seen to be a Diplohacterium 2 /x long. 

 Specimens of the same geuus and of Orchestia litforea were injected with 

 these microbes, and the resiilts surpassed the expectations of the author. 

 Of ten Talitri inoculated on the 6th of September, six commenced to 

 shine on the 8tb, and on the 9th were as bi'illiant as the first specimen 

 observed. The action of the microbe does not seem ti> become attenuated 

 in successive generations, and is not modified by being inoculated into 

 Orchestia. The light becomes so brilliant that two Talitri are quite 

 sufiicient to illuminate the face of a watch. After some days the creature 

 dies, but its corpse remains phosphorescent for some hours ; during the 



* .Tourn. Marine Biol. Assoc, i. (1889) pp. l(j2-8 (3 pis). 

 : Compti-s Keiidns, oix. (18S!t) p(). 50?i-6. 



t Ante, p. .S68. 



