SCIENCE. 
57 
experience, we suggest that it may have been the 
latter, and we do so on the following ground. 
In 1873 the Rev. W. H. Dallinger, F. R. M. S., 
undertook, with Dr. J. Drysdale, to make a contin- 
uous microscopical investigation into the life history 
of a certain species of Monas. For this purpose 
they constructed apparatus which prevented the 
evaporation of the water, and the conditions were 
made perfect, to keep the specimen in a living state 
for a considerable time under the microscope. They 
then commenced to watch the monads in turns con- 
tinuously, keeping the object in view without a 
break in observations for many days. During this 
close study of these monads, Messrs. Dallinger and 
Drysdale also observed an act so similar to that 
noticed by Dr. Leidy, that we will produce both 
statements for comparison. 
Fig. 2. 
Messrs. Dallinger and Drysdale found the modes 
of re-production with the monads to be equally as 
varied as that known to exist with the Amoeba, but 
there was one method which particularly attracted 
their attention. 
Two monads at times met and touched their 
anterior ends, swimming freely together (figure 1), 
their bodies then melted into each other , (figure 
2) ; it then became a single oblong mass, the line 
of juncture slowly disappearing, when after from six 
to 24 hours, it became rounded, (figure 3) ; at 
length the edges gave way, and myriads of minute 
points poured out, which were watched until they 
developed into perfect monads. 
In figures Nos. (5, 8, 10, 13, 15, 16, 17, 21)* of our 
illustrations may be seen in the drawings, from Dr. 
Leidy’s work, of what he observed of the mingling 
of two Amoebae ; he first speaks of their mutual 
approach, followed by an “embrace,” when the 
jointed ends of the pseudopods ftised together , 
and one sank deep into the body of the other, and 
eventually assumed the appearance of a sphere ; 
further internal breaking up was then noticed, but 
later observation was not made. This is to be 
regretted as it seems quite probable that as “ the 
melting into each other ” was proved in the case of 
the monads to be a sexual act, that the fusion , 
when noticed by Dr. Leidy in the Amoeba, may 
have been of the same character. 
The necessity for the continuous mode of study 
of such forms becomes more apparent every day, 
especially in the case of the Amoeba, for in the 
very next paragraph to that just quoted, Dr. Leidy 
states “ in my studies of Amoeba proteus I have 
not been so fortunate as to trace its history from an 
early period, nor to discover its modes of reproduc- 
tion.” 
There are other points to which we would refer, 
but having already exceeded our limit of space, we 
can only conclude by extending our thanks to Dr. 
Leidy for this his latest and most valuable contri- 
bution to Science, and to those who had the fore- 
sight and judgment to direct its publication. 
* Figures (5, 8, 10, 13, 15, 16, 17, 21) illustrate the series of changes 
observed in the swallowing and digestion of an Amoeba verrucosa by an 
A. proteus. From Bristol Marsh, Pennsylvania, August 27, 1876, 500 
diameters. Fig. (16). Amceba verrucosa^ comparatively quiescent with 
central contractile vesicle. Figs. (5, 8, 10, 13, 15, 17, 21). Successive 
changes in shape and relative position of A. proteus during the act of 
swallowing and digesting the former. Fig. (21). A . proteus approaching 
the A. verrucosa with anterior short diverging pseudopods. Fig. (8). 
The A. proteus embracing closely the A . verrucosa by a pair of digitate 
pseudopods, the points of contact of which being marked by the left hand 
arrow. Fig. (13). The A . verrucosa swallowed and forming a large 
sphere within the A . proteus. Fig. (10). The A. verrucosa^ within the 
latter, has assumed an oval form, and is contained within a vacuole. The 
central contractile vesicle, which until now had remained persistent, had 
become less distinct. Fig. (15). The A. verrucosa has assumed a pyri- 
form shape within a large elliptical vacuole and its contractile vesicle dis- 
appeared. Fig. (5). The A . proteus in the act of discharging a diatom 
while the A . verrucosa has become doubled on itself. Fig. (17). The 
remains of the A . verrucosa seen as five granular balls within the A. Pro- 
teus. Later these balls disappeared and their material appeared to be 
diffused among the granular contents of the A. proteus. 
