252 



NATURE 



\yuly 14, 1887 



body-cavity. Bacilli were also present in the blood of 

 the carp, and on one occasion four bacilli were detected 

 in a drop of blood from what appeared to be a healthy 

 roach. In some the peritoneal fluid contained numerous 

 bacilli, while in others only a few were visible ; generally 

 there was a relation between the number in the body- 

 cavity and the number in the intestine, and they were 

 most abundant in fish which had lived for some time in 

 aquaria without food ; but in trout which had been fasting 

 for at least ten days, no bacilli could be observed in the 

 peritoneal fluid. The carp which had bacilli in their 

 lalood had been living for some months in a small glass 

 aquarium. 



The difference between the roach first examined and 

 those examined subsequently led me to endeavour to 

 ascertain whether a sudden change of temperature would 

 produce any influence in the number and distribution of 

 the bacilli. As I anticipated, a rapid change from a 

 spring to a summer temperature (from 48° to 65° F.) greatly 

 diminished the vitality of all the fish experimented with, 

 except the carp ; and, as the fish became more and more 

 exhausted, the bacilli gradually increased. If the tem- 

 perature was raised from 48° F. to 65° F. in two hours, 

 the bacilli of the peritoneal fluid not only increased in the 

 roach, perch, carp, and eel, but they made their appear- 

 ance in considerable numbers in the body-cavity of the 

 trout, and on one occasion a number of small bacilli were 

 found in the blood of a trout. Although the carp seemed to 

 enjoy the rise of temperature, they were not exempt from 

 the increase of the bacteria in the blood as well as in the 

 peritoneal fluid. In some specimens of blood as many 

 as eight short slender bacilli were visible in the field of 

 the microscope at one time, and the peritoneal fluid in 

 some instances swarmed with long and short bacilli, some 

 of which were motile. 



The above observations were confirmed by cultivations 

 in gelatine agar-agar, and in infusions of fish-muscles. 

 In healthy active specimens of the roach and perch, cul- 

 tivations were easily obtained of the peritoneal bacilli, 

 and generally also from the muscular fibres lying near the 

 peritoneum, but in no instance did I succeed in obtaining 

 cultivations when the blood, or the muscles from imme- 

 diately under the skin, were used for infecting the culture- 

 media. 



Ofthe sea fish examined I have found bacilli — some- 

 times long and slender, sometimes short and thick — in 

 the peritoneal fluid and blood of the whiting {Gadus nier- 

 lajtgus), haddock {Gadus ccglefinus), cod {Gadus nior- 

 rhua), herring {Clupea harengus) ; and in the peritoneal 

 fluid only of the flounder {Platessa flessus), plaice {Pla- 

 tessa vulgaris), and lumpsucker {Cyclopterus lumpus). I 

 have not hitherto succeeded in demonstrating the existence 

 of bacteria in either the peritoneal fluid or blood of the 

 skate {Ratabatis), dogfish {Acanthias -i^ulgaris), or fishing 

 frog {Lophius piscatorius). 



There can be no doubt that the bacteria enter the body- 

 cavity by penetrating the walls of the intestine ; neither 

 can there be any doubt that, having once established 

 themselves in the peritoneal fluid, they do their utmost to 

 find their way into the blood and tissues. Notwithstand- 

 ing the presence of active bacteria in the intestinal canal, 

 and the bile and pancreatic ducts, I have failed to discover 

 either bacilli or micrococci in the bodj'-cavity of either 

 amphibia, reptiles, birds, or mammals, when in a healthy 

 condition. Hence it may be taken for granted that, in the 

 higher vertebrates, under ordinary circumstances, either (i) 

 the walls of the intestine form an effective filter or screen, 

 which prevents the passage of the bacteria into the body- 

 cavity ; or (2) that the living cells of the mucous and other 

 layers so act on the bacteria that they are destroyed 

 before they reach the body-cavity ; or (3) that the cells of 

 the peritoneal fluid effectively sterilize the bacteria which 

 succeed in entering ; or (4) that the bacteria are destroyed 

 as they pass along the lymphatics towards the general 



circulation. Most fish seem capable of tolerating the 

 presence of one or more kinds of bacteria in the peritoneal 

 fluid, whilst others can even tolerate considerable numbers 

 in their blood. It seems, however, that there is a limit 

 to this toleration ; for when the equilibrium is disturbed, 

 when by a change of the surroundings the vitality of the 

 tissues is diminished, the bacteria rapidly increase, and 

 unless the tissues as rapidly recover, the bacteria may 

 directly or indirectly cause death. 



From the observations made, it appears that bacteria 

 travel most easily along the lymphatic canals and spaces, 

 the lymph-cells being apparently less able to arrest their 

 progress than the blood-corpuscles. 



As to the nature of the bacilli found in fish nothing has 

 hitherto been determined. Olivier and Richet seem to 

 think they are neither specific nor putrefactive. At first I 

 thought they were putrefactive, but not specific. Having 

 made some further experiments, I am now inclined to 

 consider them specific and not putrefactive. It has been 

 asserted by previous writers that bacteria are always 

 present in the living tissues of fish, but this conclusion 

 should be accepted with some reserve. For example, 

 trout, roach, and eels, which were gutted immediately 

 after death, and introduced for a short time into a 5 per 

 cent, solution of phenol, and then transferred into sterilized 

 water, remained unchanged for weeks. When examined,, 

 dead bacteria were found on the surface of the skin and 

 in the peritoneal lining of the body-cavity, but no living 

 bacteria could be detected in the muscles, nor did they 

 appear in cultivations into which fragments of muscle 

 had been introduced. As was anticipated, when the fish 

 were placed in ordinary water, putrefaction at once set 

 in. Hence, in the meantime, it may be taken for granted 

 that while bacteria exist in the tissues of some fish even 

 at comparatively low temperatures, they are not always, 

 if ever, present in the tissues of others. 



THE PROGRESS OF SCOTCH UNIVERSITIES. 



"T^HE following three diagrams are meant to convey an 



-'- idea of the progress of the Scotch Universities — 



Edinburgh, Glasgow, Aberdeen, and St. Andrews — in recent 



Fig. I. — Total number of students at the four .Scotch Universities (with line 

 of population). 



years. The first shows the total number of students each 

 year from 1869 to 1885, and it appears that, with an increase 

 of population of about 18 per cent, in that period, the^ 



