Marcu# 8, 1901.] 
primary importance of anatomical characters 
as the basis of true relationship, and this book 
will do much toward dissipating the older and 
altogether fallacious idea that a classification 
of fossil plants based upon external characters 
alone is possessed of permanent value. While 
the external forms of plants or their parts may 
possess a certain value for taxonomic purposes, 
such characters are in all probability least reli- 
able in the case of fossils where they depend so 
largely upon the modifying influence of condi- 
tions under which the plant has been preserved. 
They are therefore oftentimes most misleading, 
and although we may admit their general value 
as a provisional means of classifying remains 
which cannot be otherwise distinguished, they 
possess no scientific merit and should be aban- 
doned as fast as more accurate data become 
available. 
That this book will do much to stimulate a 
more active interest in this important line of 
research we cannot doubt, but its mission will 
be wellaccomplished if it does no more than to 
finally convince botanists of their real depen- 
dence upon data derived from a study of the 
extinct forms of plant life. 
D. P. PENHALLOW. 
McGILL UNIVERSITY, 
Feb. 6, 1901. 
A Contribution to the Study of the Insect Fauna 
of Human Excrement. By L. O. Howarp. 
Proc. Washington Academy of Sciences, Vol. 
II., pp. 541-604. 2 pls. 
A brief summary of the results obtained by 
Dr. Howard in his study of the insects affecting 
human excrement was given in the Popular 
Science Monthly, January, 1901. We have now 
before us the detailed work, in which the insects 
concerned are fully discussed and in many cases 
figured. 
No resident of this country is likely to forget 
the deplorable outbreaks of typhoid fever which 
occurred in the military camps at the time of 
the war with Spain. It appears that every 
regiment in the United States service in 1898 
developed typhoid, while more than 80 per 
cent. of the deaths in camp were due to this 
disease. This condition of affairs naturally 
aroused a great deal of popular anxiety and 
indignation, while medical men bestirred them- 
SCIENCE. 
389 
selves to discover the exact causes of the spread 
of the fever. Asa result, it came to be gener- 
ally believed that flies had a great deal to do 
with the spread of typhoid bacilli, and one of 
the most prominent medical investigators con- 
eluded that ‘ flies undoubtedly served as carriers 
of the infection.’ 
Admitting, then, the agency of flies in the 
spread of typhoid fever and other ills, the 
question naturally arose, ‘What flies?’ This 
question the medical men did not pretend to 
answer, and the way was clearly open for an 
entomologist to supply the desired information. 
Dr. Howard, who loses no opportunity to make 
the Division of Entomology serviceable to the 
public, at once began an investigation which 
has now resulted in the publication of exact and 
minute details to take the place of supposition 
and vague surmise. Not only were the in- 
sects frequenting human excrement carefully 
watched and recorded, but feces were collected 
in great numbers, and the species breeding in 
them ascertained. As had been anticipated, 
flies were found in plenty; in fact, no less than 
77 different species were obtained, of which 36 
were actually found breeding in the feces. In 
addition to this, 23,087 flies were caught in 
kitchens and pantries in different parts of the 
country, in order to see how many of the kinds 
visiting or breeding in human excrement also 
visited places where food was kept, and were 
likely to crawl over the food. It appears that 
the flies most commonly found breeding in 
human excrement are not those which fre- 
quently enter dwellings, but there are several 
species which are likely to pass directly from 
the excrement to places where food is kept, and 
so become a dangerous source of infection. 
This is true of the common house fly (Musca 
domestica), the vinegar fly (Drosophila ampelo- 
phila), the stable fly (Muscina stabulans) and a 
number of others. 
The practical conclusions reached by Dr. 
Howard should become known to all municipal 
authorities. Itis shown that human excrement 
is much more dangerous to the public health 
than dead animals or other refuse. Hvery care 
should be taken to provide for its removal from 
those places where flies can gain access to it, 
and those depositing it in by-ways and vacant 
