DFCEMBER 27, 1900] 
NATURE 
an 
should undertake the improvement of the tidal portions 
of the rivers; that above this limit the local authorities 
should improve the rivers by canalisation up to a town 
conveniently situated to form an inland port, up to which 
sea-going vessels of 4oo or 500 tons could come, and which 
would serve as a distributing or receiving centre for water- 
ways of suitable dimensions penetrating into the interior ; 
and that in some cases, for surmounting high summit- 
levels, inclined planes worked by locomotives should be 
substituted for canals. Another engineer proposes that the 
Government should undertake through routes for vessels 
of 350 tons from Birmingham to Liverpool, Hull, the 
Severn, and London, and between Liverpool and Hull, and 
from London to Bristol, and considers that these main 
routes would be certain to yield a profit on the purchase 
of the existing waterways involved in the schemes and 
on the expenses of construction, which could then be 
utilised in acquiring and improving other waterways. A 
third engineer desires to make each river-basin a separate 
system; he considers that a barge of 150 tons is the 
largest barge that would pay; and instead of bringing sea- 
going vessels inland, he would bring these inland barges 
down to the tideway, where transhipment into sea-going 
craft would take place most conveniently. A fourth 
engineer considers that 1oo-ton barges are the largest size 
expedient for English inland navigation, and that in certain 
cases the improvement of canals to accommodate them 
would not pay; whilst a fifth engineer thinks that any 
improvements of inland waterways would prove an un- 
profitable and useless expenditure. 
It is evident from this summary of the views expressed 
by some of the most experienced engineers with reference 
to inland navigation, that the commissioners, after having 
collected all the evidence available, will require some time 
to formulate their recommendations, and to decide how far 
Continental practice with regard to inland waterways is 
applicable to the special conditions of the United Kingdom. 
THE SCIENTIFIC. STUDY 
DISEASES.* 
apHeE wider recognition of medical science as a rewarding 
object of endowment is a result of discoveries made 
during the last quarter of a century, and it is of interest 
to inquire why this increased knowledge should have 
borne such abundant fruit. The result is not due to any 
change in the ultimate aims of medicine, which have 
always been what they are to-day and will remain—the 
prevention and the cure of disease—nor to the application 
to the solution of medical problems of any higher intel- 
lectual ability and skill than were possessed by physicians 
of past generations, nor to the growth of the scientific 
spirit, nor to the mere fact of a great scientific advance 
in medicine, for the most important contribution ever made 
to our understanding of the processes of disease was the 
discovery by Virchow in the middle of the last century of 
the principles and facts of cellular pathology, the found- 
ation of modern pathology. 
The awakening of this wider public interest in scientific 
medicine is attributable mainly to the opening of new 
paths of investigation which have led to a deeper and 
more helpful insight into the nature and the modes of 
prevention of a group of diseases—the infectious diseases— 
which stand in a more definite and intimate relation to 
the social, moral, and physical well-being of mankind than 
any other class of diseases. The problems of infection 
which have been solved and kindred ones which give 
promise of solution are among the most important relating 
to human society. The dangers arising from the spread 
of contagious and other infectious diseases threaten, not 
the individual only, but industrial life and the whole fabric 
of modern society. Not medicine only, but all the forces of 
society are needed to combat these dangers, and the agencies 
which furnish the knowledge and the weapons for this 
warfare are among the most powerful for the improvement 
‘of human society. ; 
OF INFECTIOUS 
1 Abridged from an address delivered by Dr. W. H. Welch at the formal 
opening of the Laboratories of the Rockefeller Institute for Medical 
Research on May rr. 
NO. 1939, VOL. 75| 
Great as was the material, intellectual and social pro- 
gress of the world during the past century, there is no 
advance which compares in its influence upon the happi- 
ness of mankind with the increased power to lessen physical 
suffering from disease and accident, and to control the 
spread of pestilential diseases. 
Before some accurate knowledge of the causation of 
infectious diseases was secured preventive medicine was a 
blundering science, not, however, without its one great 
victory of vaccination against small-pox, whereby one of 
the greatest scourges of mankind can be controlled and 
could be eradicated, if the measure were universally and 
efficiently applied. The establishment upon a firm found- 
ation of the germ doctrine of infectious diseases, the dis- 
covery of the parasitic organisms of many of these diseases, 
the determination by experiment of the mode of spread of 
certain others, and the experimental studies of infection 
and immunity have transformed the face of modern 
medicine. 
The recognition, the forecasting, the comprehension of 
the symptoms and lesions, the treatment of a large number 
of infectious diseases have all been illuminated and 
furthered, but the boon of supreme import to the human 
race has been the lesson that these diseases are prevent- 
able. 
Typhus fever, once widespread, and of all diseases the 
most dependent upon filth and overcrowding, has fled to 
obscure, unsanitary corners of the world before the face 
of modern sanitation. 
In consequence of the knowledge gained by Robert Koch 
and his co-workers Asiatic cholera, to the modern world 
the great representative of a devastating epidemic, will 
never again pursue its periodical, pandemic journeys around 
the world, even should it make the start. 
Of bubonic plague, the most dreaded of all pestilences, 
which disappeared mysteriously from the civilised world 
more than two centuries ago, we know the germ and the 
manner of propagation, and, although it has ravaged India 
for the last ten years with appalling severity, it can be, 
and has been, arrested in its spread when suitable measures 
of prevention are promptly applied. 
Typhoid fever, the most important index of the geiieral 
sanitary conditions of towns and cities, has been made 
practically to disappear from a number of cities where it 
formerly prevailed. That this disease is still so prevalent 
in many rural and urban districts of the United States is 
due to a disgraceful neglect of well-known measures of 
sanitation. 
To Major Walter Reed and his colleagues of the United 
States Army Commission an inestimable debt of gratitude 
is due for the discovery of the mode of conveyance of 
yellow fever by a species of mosquito. On the basis of 
this knowledge the disease, which had been long such a 
menace to lives and commercial interests in the Southern 
States, has been eradicated from Cuba, and can be con- 
trolled elsewhere. 
Another army surgeon, M.jor Ross, acting upon the sug- 
gestion of Sir Patrick Manson, had previously demonstrated 
a similar mode of incubation and transportation of the 
parasite of malaria, discovered by Laveran, and it is now 
possible to attack intelligently and in many localities, with 
good promise of success, the serious problem of checking 
or even eradicating a disease which renders many parts of 
the world almost uninhabitable by the Caucasian race, 
and, even where less severe, hinders, as does no other 
disease, intellectual and industrial activities of the in- 
habitants. 
The deepest impress which has been made upon the 
average death-rate of cities has been in the reduction of 
infant mortality through a better understanding of its 
causes. The Rockefeller Institute, by the investigations 
which it has supported of the question of clean milk and 
of the causes of the summer diarrhceas of infants, has 
already made important contributions to this subject which 
have borne good fruit. 
No outcome of the modern science of bacteriology has 
made a more profound impression upon the medical pro- 
fession and the public, or comes into closer relation to 
medical practice, than Behring’s discovery of’ the treatment 
of diphtheria by antitoxic.serum, wherebv in the last twelve 
