ZOOLOGY AND BOTANY, MICROSCOP T, ETC. 
637 
Protozoa. 
Infusoria Aspirotricha.* — Those of our readers who are interested 
in this group of Infusorians, the Holotricha of many authors, may be 
glad to know that a monograph of the group has been prepared 
by a Russian naturalist, whose name w r e are too ignorant to decipher ; 
the text being wholly in Russian is beyond our powers, but we may be 
allowed to admire the figures. 
Regeneration of Stentor.f — Mr. F. R. Lillie has a memoir on the 
smallest part of Stentor capable of regeneration, as a contribution on 
the limits of divisibility in living matter. After citing the observations 
of those who have addressed themselves to this subject, he tells us that 
the numerous experiments which he made, and which involved the use 
of many hundreds of S. polymorphus, showed that the smallest parts 
capable of regeneration possess the volume of a sphere of about 80 p 
in diameter. Fewer experiments on a smaller number of S. cseruleus 
yielded results almost identical. The main results hitherto reached on 
the merotomy of the Protozoa are summarised as follows : — A large 
number of authors have shown that cytoplasm without nucleus is in- 
capable of regeneration. This Mr. Lillie is able to confirm, as also 
the statement that a nucleus without cytoplasm is incapable of regener- 
ation. To the accepted statement that portions of the body consisting 
of nucleus and cytoplasm are capable of regeneration, the author would 
add the rider, provided that the amount of cytoplasm exceed a certain 
minimal volume. This, the author thinks, amounts to a demonstration 
of Yerworn’s view that regeneration in the Protozoa is due to the 
reciprocal interaction of nucleus and cytoplasm. Organisation resides 
in the cytoplasm as well as in the nucleus. How otherwise, he asks, arc 
we to explain the fact that a difference in the amount of cytoplasm alone 
determines the occurrence of regeneration ? 
With regard to the limits of divisibility in living matter, Mr. Lillie 
was not concerned with the question of the ultimate constitution of 
protoplasm, but merely with the question, what is the order of magnitude 
of the smallest particle that can show the phenomena of life ? In the 
case of the animal ovum, it has been noted to be about one-fourth of its 
volume, but in Stentor the volume is relatively considerably less. In 
the case of the animal ovum, parts slightly smaller than the minimal 
necessary for complete development may undergo partial development, 
and parallel phenomena are to be found in Stentor. It is probable that 
there is for each species of animal a minimal mass of definite size, 
consisting of nucleus and cytoplasm, within which the organisation of 
the species can find its latent expression. 
Conjugation of Actinophrys sol.J — Hr. Fr. Schaudinn points out 
that no one has hitherto satisfactorily demonstrated the fusion of nuclei 
in conjugating Rhizopods, and that only Wolters has proved this for 
Gregarines ( Monocijstis ). Now, however, Schaudinn has succeeded with 
Actinophrys sol Ehrbg., which he fixed with hot alcohol-sublimate and 
stained with ammoniacal-iron oxide and haematoxylin according to the 
* Mem. Acad. Imp. Sci. St. Petersburg, iv. (1896) 395 and 13 pp. (7 plates), 
t Jouru. Morphol., xii. (1896) pp. 239-49. 
SB. K. Preuss. Akad., 1896, pp. 83-9 (6 figs.). 
