516 SUMMARY OF CURRENT RESEARCHES RELATING TO 
minent on the title-page of his last work. The idea is no new one ; 
Nageli was one of its exponents ; it has cropped up in many guises ; 
what Eimer tried to do was to prove its reality. 
Organisms grow, and vary progressively in definite directions, defined 
by external conditions ; at certain stages of stability there is a stoppage 
in the process, and species arise by “ genepistasis.” This is the central 
thesis, which we have previously summarised ; the aim of the book is 
to show the adequacy of the theory as an interpretation of Lepidoptera. 
The chapters deal with the following subjects : — the theory of 
orthogenesis and the limits of natural selection ; criticism of Weis- 
mann’s “ germinal selection ” theory ; origin of leaf-like characters ; 
types of marking and pseudo-mimicry ; mimicry ; succession of colours 
and markings ; sexual dimorphism and selection ; climatic influences as 
factors in evolution. 
X' We cannot agree with the late Professor’s collaborates Dr. C. 
Fickert that “ the book furnishes incontrovertible proofs of the inherit- 
ance of acquired characters aud a complete refutation of Weismannian 
speculations ; ” but it is a careful attempt to vindicate a position in which 
there is doubtless some truth, if we could only get at it. It will remain 
as a memorial of a devoted and courageous student of evolution who was 
not afraid to be in a minority. 
Physiological Import of Maturation.* — Dr. N. Iwanzoff has studied 
this in Holothuria tubulosa and other Echinoderms. The immature ova 
form pseudopodia when surrounded with spermatozoa, and the younger 
the ovum, the greater is the mutual attraction, and the more intense 
the production of pseudopodia. In the case of very young ova, however, 
the pseudopodia are few or absent. In quite ripe eggs, again, there is 
but one pseudopodium — the receptive protrusion — which is relatively 
small. The spermatozoa which are taken in by the immature ova serve 
as food and are digested. The process of maturation weakens the 
vitality of the ovum by the elimination of an important part of the 
nucleus, and that in such a way that the ripe ovum is unable to digest 
the spermatozoon. Fertilisation is fundamentally a nutritive process. 
Germinal Vesicle and Polar Bodies in Urodela-f — Profs. J. B. 
Carnoy and H. Lebrun continue their investigation of the germinal 
vesicle and polar bodies in Amphibia, the present memoir dealing with 
the axolotl and the newts. The nucleoli are definitely nuclein-bodies ; 
the structure of the cytoplasm and nucleoplasm is reticular not alveolar; 
the nuclein ribbon is typical and apparently continuous, and gives rise 
at an early stage to a few primary nucleoli, or sometimes is wholly 
resolved into these ; in any case the ribbon is resolved, and disappears 
as such, some of the granules forming secondary nucleoli. 
From this point onwards, until the occurrence of the polar kineses, 
all the figures are nucleolar, one set succeeding another in ephemeral 
sequence, of which the authors give a detailed description. It is errone- 
Unter Mitwirkung von Dr. C. Fickert.’ Leipzig, 8vo, x., xvi., and 513 pp., 2 pis., 
235 figs. See Zool. Centralbl., v. (1898) pp. 241-51 ; Biol. Centralbl., xviii. (1898) 
pp. 403-16, 444-56. 
* Bull. Soc. Imp. Nat. Moscou, 1897 (published 1898), pp. 355-67 (1 pi.). 
f La Cellule, xiv. (1898) pp. 113-200 (4 pis.). 
