ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
393 
peculiarity of the epitokous segments lies in the fact that they do not 
bear modified parapodia and specialised chaetee as in other Polychaetes, 
but owe their motility entirely to their narrow and elongated form. 
Again, the two forms of epitoky familiar in the Polychaetes are repre- 
sented on the one hand by Nereis, where certain of the segments become 
sexually mature but are not separated from the atokous segments, and 
on the other by the Syllidae, where the epitokous segments separate 
and bud out a head. In Eunice viridis we have a stage intermediate 
between the two. It is probable that in it as in the Syllidae the atokous 
segments survive the separation of the epitokous region, and possess the 
power of forming new segments ; the free epitokous region, on the other 
hand, probably dies after the liberation of the genital products. It 
exhibits a well-marked tendency to break up into fragments. In the 
case of the “ Heteronereis ” of the Nereids the whole animal dies after 
the emission of the genital products. 
Prof. Ehlers is not satisfied that the ventral organs of the palolo 
are true “ eyes,” but has no suggestion to make as to their function. 
Swarming of the Palolo. — Dr. B. Friedlander* has a further paper 
on the exact cause of the appearance of the palolo worm at the surface, 
and on the influence of cosmic influences on the precise time of ap- 
pearance. He has made an elaborate series of calculations to illustrate 
the dependence of other physiological phenomena on cosmic influences, 
as exemplified especially by the relation between birth-frequency and 
the state of the moon. The result is to show that the Samoan tradition 
that births are more frequent in the hours of rising than of falling tide 
has a basis of fact. A close examination of the palolo phenomena shows, 
however, that the swarming is not directly dependent upon the tides, 
or at least cannot be wholly explained by them. 
Recently, Herr Svante Arrhenius f has published a paper arguing 
that the changes of the moon produce variations in the atmospheric 
electricity which have an important influence on living organisms. 
Without committing himself entirely to the acceptance of this position 
as an explanation of the appearance of the palolo, the author points out 
that there are many periodic organic phenomena, such as the periodicity 
of births, the movements of internal parasites, epileptic fits, &c., whose 
regularity is unexplained. To say that the appearance of the palolo is 
due to cosmic influences is only to say that in common with many other 
periodic organic phenomena its exact causation is unknown. 
The remainder of the article is devoted to a reply to Kramer’s J paper, 
many of whose criticisms and observations are said to be answered by 
the authoritative statements of Prof. Ehlers. Friedlander believes that 
there can be no doubt that the true palolo is Eunice viridis , but the 
material may also contain a few headless fragments of another w r orm 
(“ pseudo-palolo ”) which is probably a species of Lysidice. 
Vascular and Excretory Systems of Sipunculus.§ — Herr S. J. 
Metalnikoff describes the “urns” of the blood in Sipunculus nudus , 
S. tesselatus , and Phymosoma. They differ in these three cases. 
* Biol. Centralbl., xix. (1899) pp. 241-69. 
t Skand. Arch. f. Phy;-., viii. (1897) p. 367. X Cf. this Journal, ante, p. 282. 
§ MT. Zool. Stat. Neapel, xiii. (1899) pp. 440-7. 
