Fume 30, 1870] 
NATURE 
173 
the mass becomes divided into an aggregation of rounded or 
ovoid bodies each about 545,” in diameter. As these subdivisions 
are taking place, the mass as a whole separates from the un- 
altered pellicle by which it is surrounded. Occasionally there is 
Fic. 1.—Development of Unicellular Organisms: three areas of differen- 
tiation showing different stages. 
the most distinct interval, at a certain stage, between the parent 
pellicle and this differentiating mass, whose subdivisions also 
gradually separate from one another, These subdivisions now 
appear as independent unicellular organisms, bounded by a deli- 
cate membrane, and containing, perhaps, from four to eight of 
the altered monads and bacteria in their interior. 
Throughout the winter months, such areas of differentiation 
and such resulting unicellular organisms were frequently met 
with. The unicellular organisms seem during such weather to 
persist fora very long time in this condition, merely, perhaps, 
increasing somewhat in size, and most of them ultimately become 
disintegrated without undergoing further development. They 
were always seen in a completely motionless condition, and 
presented no trace of a cilium, so that they were altogether 
different from the creature known as A/onas fens. In one 
solution of hay in which such organisms had been present for 
some time, after a few days of warmer weather, several of 
them were found to have become spherica!, and to have under- 
gone a considerable increase in size. Some of these were as 
much as s;/;,” in diameter, andon one occasion a stage in the 
actual transition of one of these unicellular organisms into an 
Amaeba was seen with the most perfect distinctness. One 
Fic. 2.—Refres2nting gradual enlargement of Unicellular Organisms, and 
conversion of one of them into an Awaba. 
half of the organism was distinctly amoeboid in character, whilst 
tie other half was almost unchanged, containing large granules 
like those in the unaltered cells. As slow alteration in shape, 
of a slug-like character, took place in the anterior diapha- 
nous protoplasmic portion, slow rolling movements occurred 
amongst the granules in the posterior cell-like portion, whose 
matrix seemed to have been rendered more fluid. I watched this 
organism for about half an hour, and then, wishing to examine 
other portions of the specimen of pellicle in which it had been 
contained, I moved the glass and was afterwards unable to find 
this particular specimen again, Unfortunately, I could discover 
no other Amcebze or transition states.* 
In other cases the areas of differentiation, commencing in a 
somewhat similar way, terminate in the production of spores of 
fungi, and I will now describe the mode of evolution of such 
spores as I observed it taking place in portions of a pellicle 
having a brownish colour, from an old infusion of hay. The 
development of this brownish tinge in the earlier stages made it 
more easy to unravel the nature of the earlier changes. The 
areas which began to differentiate were generally not very large. 
They were at first quite colourless, and the granules were sepa- 
rated from one another by a notable amount of transparent jelly- 
* Prof. Hartig has, however, described a similar mode of origin of Amcebae 
from unicellular organisms, in his observations on the phytozoa of 
Marchantie. See Fournal of the Microscopical Society, 1855, p. 5%. 
like material. The granules themselves were mostly shaped like 
the figure 8, and each half was about 35400" in diameter. A later 
stage was seen, apparently, in other areas which had assumed a 
yery faint brownish tinge, and which presented evidences that 
Fic 3.—Mode of origin of Spores of Fungi out of differentiating portions of a 
Pellicle formed on an infusion of hay. 
subdivision was taking place. As the process of subdivision pro- 
gressed, so the brown tinge became gradually deeper. Ovoid 
masses were frequently seen about 35” Or tes” in diameter, 
of a decidedly brown colour, with from 8 to 12 or more ovoid 
subdivisions within the common envelope. As multiplication 
advanced, the individual products lost all trace of their original 
granular condition. They became quite homogeneous and highly 
refractive masses of a brown colour, looking almost like large 
brown fat globules. At last, multiplication still proceeding, the 
distended, and always thin, cyst-like, general envelope becomes 
ruptured and disappears, leaving only an irregular mass of 
spherical or ovoidal bodies of various sizes. The individual 
segments, aS soon as this process of multiplication has ceased, 
increase in size, and then gradually become less refractive and 
lighter in colour, A slight differentiation of their contents also 
again takes place, marked by the appearance of faint lines 
within, as they assume the appearance of ovoid bodies about 
soon’ in diameter.* Even when they have attained this stage 
of development, they may again undergo a process of division ; 
though generally, after a time, they give origin to ordinary 
mycelial filaments. 
Similar changes in the refractive index have been frequently 
noticed in other cases when a protoplasmic mass is at the same 
time differentiating and undergoing a process of multiplication, 
whilst the mode and frequency of the sub-division is exactly 
comparable with what so frequently happens to the gonidia of 
lichens. 
The changes which I have described represent, I think, only two 
extreme types of a mode of metamorphosis which is apt to take 
place in portions of the pellicle. In the one case a certain area 
of the pellicle, after undergoing some changes, resolves itself into 
a number of ovoid bodies, which collectively are about equal in 
bulk to the altered area itself; whilst, in the other case, at 
different stages, the segments of the altered area undergo a 
process of growth and sub-division, so that ultimately the mass 
of spores which results far exceeds in bulk that of the original 
area when it began to undergo change. 
At other times intermediate processes are met with, and then 
fungus-spores are produced after a fashion more closely resem- 
bling that which leads to the production of the unicellular 
organisms above described. The areas of change are then larger 
than those last described, and colourless throughout, whilst the 
processes of growth and multiplication are Jess marked at the 
different stages. Where fungus-spores result after this fashion, 
the changes in the refractive index, and the homogeneous appear- 
ance ‘previously alluded to, still generally manifest themselves 
at the ultimate stage of division, though nothing of this kind 
shows itself in the more simple process leading to the produc- 
tion of the unicellular organisms. 
Now, however mysterious the nature of these changes may he, 
which take place, as it seems to us, ‘“‘spontaneously” in the 
pellicle on the surface of a solution of organic matter, they are 
exactly comparable with other changes occurring within the 
terminal dissepiments of a kind of submerged mucor, named 
Achlya prolifera, similar to those which occur within the thecze 
of certain ‘other fungi and of certain lichens, and altogether 
analogous to that which, as Prof. Haeckel says, takes place in 
* The markings of these spores are more obscure and less regular than 
they are represented (/) in the woodcut. 
+ See Nicolet, in Thompson’s Arcana Nature, 1859. 
