530 
to concentrate attention on the pathological 
aspects of the enquiry. As to the nature 
of the disease, Hartshorne writes, with com- 
mendable caution, “It is only possible to 
speculate at present. It is most probable 
that ague is a toxemic neurosis. The im- 
portance of the blood change attending it 
is shown by the disintegration of the blood 
corpuscles, and deposit of pigment in vari- 
ous organs.’”’ This destruction of the blood 
corpuscles was the critical point on which 
the investigation turned. About 1880, 
Laveran, a French army surgeon, discov- 
ered the destructive agency in a minute 
parasite, one of the protozoa, which takes 
up its residence in, and then, ungratefully 
enough, destroys, our red blood corpuscles. 
What a splendid problem was presented by 
the facts thus brought to light! The exqui- 
site refinement of the researches which fol- 
lowed may be inferred when we reflect on the 
minuteness of an organism which can work 
out a part of its life history within blood 
corpuscles so small that four to six millions 
of them find plenty of room ina cubic milli- 
meter. But stranger still is the fact, estab- 
lished within the past year or two, that the 
mosquito plays the rdle of an intermediary 
host and transmits the parasites to us while 
feasting upon our blood. The details of 
this remarkable discovery need only be al- 
luded to here, for they have been so recently 
explained by the experts participating in 
them that their essential features are a part 
of popularinformation. Suffice it to remark 
that they show how we may secure almost 
complete immunity from malarial fevers at 
no distant day. 
Thus, in whatever direction we look for 
the sources of scientific progress, the same 
elementary methods of advancement are 
found to be effective. Whether we consider 
the dimensions of the solar system or the 
distances between the molecules of a gas; 
whether we seek the history of a star as re- 
vealed by its light or the history of the 
SCIENCE. 
[N.S. Vou. XIII. No. 327. 
earth as recorded in its crust; whether we 
would learn the evolution of man or the de- 
velopment of a protozoon; whether we 
would study the physical and chemical 
properties of the sun or the corresponding 
properties of a grain of sand; in short, 
whether we turn to the macrocosm or to 
themicrocosm for definite, verifiable, knowl- 
edge, it is found to originate in and to ad- 
vance with observation and experiment. 
R. 5. Woopwarp. 
ON THE HOMOLOGIES AND PROBABLE ORI- 
GIN OF THE EMBRYO-SAC.* 
THE problems connected with the origin 
and interpretation of the embryo-sac have 
been of great interest to the student of 
plant morphology, from the time that they 
began to inquire into the relation of the 
ovule to the formation of the embryo plant. 
It is now a matter only of historical inter- 
est that Morland (1702), Geoffrey (1714) 
and others contended so seriously that the 
embryo-sac of the angiosperms was a sort of 
incubator where the embryo, brought in by 
the pollen tube, was hatched out into the 
young plantlet. While great advances have 
been made in our knowledge of the devel- 
opment and function of the embryo-sac, 
there are still unsettled problems of its 
origin and homology upon which we specu- 
ulate, perhaps with no nearer approach to 
the truth than were the speculations by 
the founders of the science of plant mor- 
phology. 
The first important contribution to the 
morphology of the embryo-sac was made by 
Hofmeister during the middle of the present 
(19th) century, extending over a period 
from 1849 (Die Entstehung des Embryo der 
Phanerogamen) to 1861 (Neue Beitrage zur 
Kenntniss der Phanerogamen). In the 
* Paper presented before the joint session of Section 
G, American Association for the Advancement of Sci- 
ence, and the Botanical Society of America, at its sixth 
annual meeting, New York City, June 28, 1900. 
