50 



Proceedings of Learned Societies. 



[Aug. I, 



ty-four hous is fufficient, no fufpicion is 

 entertairhed of tiic caufc ot'ilie fVecjuency 

 and dilirefa in palTuig it, and (l;e fyaip- 

 toms are rcterrcd to an initable ftate 

 of tiie coats of the bladder. It; is 

 only by drawing oft' the urine through a 

 catheter that the difeafe in this lobe can 

 be afcertained, as in that way alone the 

 quantity of urine which is retained can 

 be deLermined. No extunination per 

 auiim can give the furgeon any informa- 

 tion on this fubject, lince tlie pnftcrior 

 furface of the viij'a deferentia only is felt, 

 if the finger Ihouid reach fo far ; and yet 

 it is in tliis way that practitioners in ge- 

 neral pretend to judge of the greater or 

 lefs degree of the difeafe, although that 

 portion of the gland whicli forms the mofl 

 important part of the complaint is whol- 

 ly out of their reach. 



The Icall prqjettion of this lobe into 

 the bladder ftretchcs tlic internal mem- 

 brane of that viicus wiiich palfcs over it, 

 keeps it in a ftate of irritation, and makes 

 it liable to be grafpcd by the ai'lion of 

 the fphinder mufcie in expelling tlic lail 

 drops of urine, fo as to give the patient 

 excrnciating pain. When it is more en- 

 larged, the fymptoins go off. 



From thefe obfervations it appears 

 that this fmaJl lobe of the prollate gland, 

 which has been overlooked, is, from the 

 fituatiou and ciicuniliances in which it is 

 placed, more liable to become dileafed 

 than any otlier part of the glanrl, and 

 produces fymptoms of danger and diftrefs 

 peculiar to itfelf, which have been hither- 

 to fuppofed to arife from the body of the 

 gland becoming enlarged. 



The laft Croonian Letture delivered to 

 the Royal Society was on the Arrange- 

 ment and Mechanical A6tiou of the JMuf- 

 cles of Fillies, by Antuot.y Carlisle, 

 F,fq. The mufcles of fiflics are of a very 

 different conftruction from thofe of tiie 

 other natural clairce. The nicdiiun in 

 \A-hich thefe animals rotide, the form of 

 their bodies, and the inllruments employ- 

 ed for their progreffive motion, give them 

 a character peculiarly diliinit from the 

 rell cf the creation. The liame-work of 

 bones or cartilages is finiple ; the limb.s 

 are not formed for complicated motions ; 

 and the proportion of mulciilar flelli is 

 remarkably large. The mufdcs of fillies 

 have no tendinous chords, their infer- 

 t ons being alv. ays Helhy. There are, 

 however, femi-tianfparent pearly tendons 

 placed between the plates of the mufcles, 

 which give origin to a feries of fhort mul- 

 cular fibres paiFiag nearly at right-angles 



between the furfaces of the adjoining 

 plates. 



Ihe motion of a round-fliaped fifli, in- 

 dependent of its fiiib, is hmple; and as it 

 is chietly ellctted by the lateral flexure of 

 the fpiiie and tail, upon winch tlie great 

 iiiafs of its mufcular flelli is employed, 

 wiiilll the tins arc moved by fmall muf- 

 cles, and thofe, from their pofitiou, com- 

 paratively but of little power. 



Mr. C. firft defcribes the tins, the pur- 

 pofcs to whicii they are employed, and 

 the mufcles attached to them ; and then, 

 in order to alccrtain the effect of the fins 

 on the motions of fillies, he performed a 

 variety of experiments. A number of 

 living dace, of an equal fize, were put in- 

 to' a large veffel of water. The pectoral 

 fins of one of thefe were cut off, and it 

 was replaced with the others ; its pro- 

 grelfive motions were not at all impeded, 

 but the head inclined downwards, and 

 when it attempted to afcend, the effort 

 was accompliflied w ith dilHculty. 



The pectoral and abdominal fins were 

 then removed from a fecond fifli. It re- 

 mained at the bottom of .the veifcl, and 

 could not be made to afcend. Its pro- 

 greffive motion was not perceptibly more 

 (low ; but when the tail aCted, the body 

 fliewed a tendency to roll ; and the fingle 

 fins were widely expanded, as if to coun- 

 teract this effect. 



From a third fifli the fingle fins were 

 taken off, which produced a tendency to 

 turn round, and the pectoral fins were 

 kept conftantly extended to obviate that 

 motion. 



From a fourth fifli the peftoral and ab- 

 dominal fins were cut off on one fide, 

 and it immediately loft the power of 

 keeping its back upwards. I'he fingle 

 fins were expanded ; but the fifli fwam 

 obliquely on its fide, with the remaining 

 pectoral and abdominal tins downvvards. 

 From a fifth filb nil the fins were re- 

 moved. Its back WHS kept iii a vertical 

 pofition, \vhilft at rell, by the cxpanfion 

 of tlic tail ; but it rolled half round at 

 every attempt to move. 



From a hxth fifli the tail was cut off 

 clofe to the body. Its progreifive mo- 

 tion was confiderably impeded, and the 

 flexions of the fpine were much increafed 

 during the endeavour to advance ; but 

 neither the pectoral nor abdominal fins 

 leemed to be more actively cm[iloycd. 



From a fevcnth filh all the fins and the 

 tail were removed. It remained almofb 

 without motion, floating near the furface 

 of the water, with its b.lly upward. 



