326 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
nearest the light, and the application of heat did not drive them away. 
As Engelmann has found that sensitiveness to light is stronger with a 
partial pressure of oxygen greater than the normal, this must also be 
considered. The relations of thermotaxis and heliotaxis require further 
working out. 
Filament-spores of the Microsporidia.* — By treating the spores of 
the pebrine parasite with strong nitric acid, M. P. Thelohan has found 
that, under the influence of this reagent, the spores swell up, acquiring 
double their original bulk, while at the same time they become extremely 
pale. Within the spore there is a highly refracting pyriform capsule, 
which occupies about two-thirds of the interior of the cavity. By the 
side of this are usually two or three collections of protoplasm coagulated 
by the acid. To a large number of spores is attached a filament, which 
attains a length three or four times the original length of the spore, 
12-15 jx. By the extrusion of this filament the capsule diminishes 
in bulk, and becomes much less refractive. Thus the spore of the Micro- 
sporidia has quite the same structure as that of some of the Myxosporidia, 
e. g. Glugeidse. 
Nucleus and Nuclear Division in Benedenia.f— M. A. Labbe, 
finding examples of this genus which were more than 1 mm. long, was 
able to make serial sections, and so to study their structure and develop- 
ment. He finds that most of his predecessors are wrong. The nucleus 
of young specimens of Benedenia does not agree at all with the descrip- 
tions given by Schneider. Whether rounded or oval, it has a membrane, 
a very fine reticulum, and a large nucleus. As the Coccidium grows it 
passes through a certain number of stages which M. Labbe proposes to 
call premitotic. First of all the karyosome degenerates and undergoes 
fragmentation ; it becomes hollowed by a vacuole formed by other 
karyosomes, which in their turn break up and fill the nucleus with their 
debris. These karyosomes he calls primary karyosomes, and they can 
be stained by acid substances, which is an indication of their retrograde 
state. There next appear very small karyosomes varying from 1 to 6 /x. 
These secondary karyosomes are basophile. The nucleus in this stage 
is irregular in form. At the centre there are one or more primary 
karyosomes more or less degenerated, together with extremely delicate 
fibrils, and, lastly, closely applied against the membrane of the nucleus 
are the secondary karyosomes. These vary much in number and size. 
When a nuclear division is going to take place the nuclear membrane 
breaks, the nucleus becomes stellate in form, the primary karyosomes 
pass into the cytojdasm, or are partially dissolved in the enchylema. 
A curious phenomenon may now be observed : part of the nuclear 
elements emigrate to a point of the periphery where they form a 
stainable mass, which is not a nucleus, and which does not persist. 
Meantime, at the centre of the protoplasm there remains a rounded or 
ovoid mass which is very difficult to stain ; it contains fine and numerous 
granules, and is surrounded by a solid zone of an amorphous, coloured 
enchylenja. The author refrains from explaining the phenomena which 
he has observed, but promises us a more detailed account. 
* C.R. Soc. Biol, de Paris, 1894, pp. 505-6. Cf. this Journal, 1894, p. 465. 
t Comptes Rendus, cxx. (1895) pp. 381-3. 
