190 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
form is quite different from the other species of the genus. It is much 
larger than E. dicJiotoma, and has a much larger number of tentacles, of 
which there may be as many as fourteen. The tentacles are characteristic 
in form, for they are very long and only divide at the end ; their number 
is always greater than that of the radial canals, and the two structures 
have no regular topographical relation to one another. The most in- 
teresting point in E. claparedii is the example it affords of the change of 
function of an organ ; its rudimentary bell which has ceased to serve as 
a swimming organ has taken on a new function, for it shuts off a space 
into which the young Medusae enter, and where they, protected from 
injuries of all kinds, pass through an undisturbed development. Dr. 
Hartlaub gives the specific characters of this species and also of the 
Eleutlieria dichotoma of Quatrefages. 
Abnormal Hydromedusae.'*' — Prof. W. C. MTntosh gives an account 
of some abnormal, mouthless. Hydromedusae which were obtained in 
St. Andrews Bay. In considering how they manage to exist he refers 
to Mereschkowsky’s suggestion that “ the Medusa can nourish itself by 
means of its ectoderm by absorbing the organic material dissolved in the 
sea-water.” The remarkable tenacity of life exhibited by certain marine 
animals confined in pure sea-water lends some countenance to the notion. 
As the Hydromedusae are generally somewhat voracious forms, it is 
possible that mouthless examples may, by contracting the disk, fold 
themselves over prey of various kinds, and thus directly absorb nourish- 
ment through the ectoderm. 
Porifera. 
Physiology of Sponges.f — Dr. E. von Lendenfeld gives a detailed 
account of his experimental investigations on the physiology of Sponges. 
He first made a series of feeding experiments with carmine, starch, and 
milk, which were introduced into the sea-water in small quantities, and 
kept mixed with it by a constant stream of air. Fresh living sponges 
were put into these mixtures and removed after a time, which varied from 
1^ to 36 hours ; they were then prepared in various ways and afterwards 
cut into series of sections ; by these means it was possible to follow the 
ingestion of the food-substances and their course in the sponge-body. 
The action of various poisons was next investigated. In all, 149 
experiments are described. 
The first result of the suspension of solid bodies, such as carmine or 
starch, in water, is the contraction or closure of the dermal pores ; this 
may be regarded as a reflex movement of the sphincters at the pores. 
Later on, the pores widen again somewhat in consequence either of the 
sponge being unable to forego the stream of water for more than two or 
three hours, or to the fatigue and relaxation of the sphincters. The 
soft milk spheres, which may be regarded as fluid, do not usually affect 
the sphincters so powerfully as the grains, and there is, consequently, 
no reflex movement to close the pores. 
The results are set out in tables and are critically considered ; their 
study leads the author to conclude that : — 
(1) The ingestion of nutriment goes on in the interior of the sponge 
* Ann. and Mag. Nat. Hist., v. (1890) pp. 40-3. 
t Zcitschr. f. Wis.g. Zoul., xlviii. (1889) pp. 400-700 (15 jds.). 
