4 SI 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
panied by a certain quantity of the surrounding water. Those that form 
currents around their mouth (“ Infusoires a tourbillon ”) only seem to 
stop taking in particles when a kind of plethora appears to mechanically 
stop the formation of fresh vacuoles. Those that seize their food (“ In- 
fusoires capteurs ”) appear to make a selection ; non-nutrient substances 
are only taken when they are attached to those which are really nutritious. 
In all cases studied the digestive vacuole was the seat of an acid secretion 
which first neutralizes the alkaline water and then makes the contents of 
the vacuole acid. This secretion goes on with the same intensity whether 
the contents of the vacuoles are animal, vegetable, or mineral. This acid 
appears to be strong, but the rapidity with which it is secreted varies 
greatly in different species ; and there is, also, a difference in the toxicity 
of chemical substances introduced into their bodies, which points to a 
considerable amount of difference in the constitution of the protoplasm. 
Conjugation in Eoctiluca.* — Dr. C. Ischikawa points out that in 
the conjugation of Noctiluca rniliaris the two nuclei of the copulating cells 
do not fuse but remain lying against one another till the mass divides 
again ; division of the nuclei then takes place in such a way that half of 
each nucleus passes into each of the two resulting pieces. 
When conjugating, a connecting bridge is formed between two 
individuals, and the two protoplasmic masses become one. Fusion goes 
on till a single body is formed. After repose the author often noticed 
rounded protoplasmic spheres, which stained intensely with methyl- 
green, close to the poles of the axis in which the two cells touched. 
These bodies may be centrosomata. The binucleated individual differs 
in no other particular from a form with a single nucleus ; it possesses a 
new mouth, tentacle and flagellum, and for two days it may show no 
inclination to divide ; others divide directly after copulation. 
Sporulation does not occur until after division, and not then always 
in the same way exactly. In budding the nucleus becomes more obscure, 
but does not disappear, and the whole of the nucleus gradually passes 
into the buds, so that at the end of the process no protoplasm or nuclear 
substance remains over. 
Pathogenic Protozoa.j — Dr. L. Pfeiffer, in discussing the pathogenic 
protozoa in relation to our present knowledge of contagious and mias- 
matic diseases, seems inclined to award them a prominent position among 
the causes of infectious disorders, and this chiefly on account of the 
mobile swarming stage in juvenile conditions of Coccidia. This mobile 
period of the larval stage, described by Dr. E. Pfeiffer in 1890, the 
author is disposed to regard as having a peculiar significance, and as 
capable of explaining the malignancy of certain diseases. The actual 
number of facts at our disposal is, however, small, and many even of 
those are disputed; it is well, however, to have attention called to 
a few positive data pointing in a certain direction, as well as to the 
inability of bacteriology to explain numerous disorders. 
* Zool. Anzeig., xiv. (1891) pp. 12-14 (4 figs.). 
t CentralbL f. Bakteriol. u. Parasitenk., viii. (1890) pp. 761 and 794. 
