408 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
appears, however, as thickenings of these threads, not between them as 
Flemming stated. The author argues that it is not merely an “ atavistic 
reminiscence.” It has probably some functional import, and the sug- 
gestion is offered that it is an accumulation and condensation of used-up 
material from the achromatin apparatus, in short, “ that it is an excretory 
product.” 
Relation of Centrosomes to Cilia.* * * § — Dr. L. F. Henneguy notes 
several facts which point to a physiological relation between centrosomes 
and cilia. Thus, in the ciliated cells of Lamellibranch gills, the swelling' 
at the base of each cilium behaves to reagents exactly like a centrosome. 
The same relation is suggested by the centrosome in spermatozoa. 
“ The centrosomes, which have been hitherto regarded by the majority 
of biologists simply as organs playing a part as kinetic centres, having 
to do with the regulation of the movements within the dividing cell, 
should also be regarded as kinetic centres for the external movements of 
the cell.” 
Cuticle and Intercellular Bridges.f — Prof. F. K. Studnicka main- 
tains that the cuticle or Declcplatte, with its vertical striae, must be 
interpreted in relation to the intercellular communications in the epi- 
dermis, and that it is primitively due to fine membranes connecting cilia. 
The septa in the Deckplatle , the intercellular connections of epidermic 
cells, and in part even the cilia, are morphologically equivalent. An 
ingenious figure in the text illustrates the theory. 
Chondrified Fibres in Connective Tissue.^ — Prof. F. K. Studnicka 
found in the lamprey and hag somewhat mysterious chondrified fibres 
in the connective tissue. They did not, except in rare cases, show any 
direct connection with cells. What part, if any, they may play in 
chondrification, remains obscure. 
Alimentary Tract of Chelone.§ — Prof. L. Plate gives a short account 
of the alimentary tract of Chelone mydas , the minute structure of which 
does not seem to have been adequately studied as yet. Roundish papillae 
in the mouth-cavity often show a central insinking, which C. K. Hoff- 
mann interpreted as the opening of small glands ; but sections show no 
trace of glands. The long horny papillae of the gullet were interpreted 
by Owen as assisting the downward passage of the slippery seaweed ; 
but Plate thinks that they must help rather to tear it up. 
Enamel of Elasmobranch Fishes. || — Mr. C. S. Tomes discusses the 
nature of the hard polished outer layer of the teeth in Elasmobranchs 
which resembles an enamel in hardness, optical properties, almost entire 
solubility in weak acids, and tubularity, but contains lacunar spaces and 
presents a very distinct lamination. Upon the balance of its characters 
it has much more in common with enamel than with dentine, from which 
it is sharply marked off by the entire absence of any collagen basis. 
As to development, it seems to be a joint product of the epiblastic 
enamel organ and the mesoblastic dentine papilla. On the whole, how- 
* Comptes Kendus, cxxvi. (1898) pp. 975-8. 
t SB. Bohm. Ges. Wiss., 1897 (ii.) No. lix. 11 pp., 1 pi. and 1 fig. 
% Op. cit., 1897 (ii.) No. lxv., 7 pp. 
§ SB. Ges. Nat. Freunde Berlin, 1897, pp. 85-9. 
It P. ft. Soc., lxiii. (1898) pp. 54-6. 
