BIOLOGY. 
Spong . 9 
the body- wall ; this is the place where afterwards, on the sixth day after 
fixation, the osculum is formed. The adjacent dermal cells produce the 
oscular chimney, which is free from collar cells. The gastral cells 
become shorter and are transformed into collar cells. In other Asconidcc 
immigration of cells from the dermal layer into the interior takes place 
at various points all over the surface. After fixation the flagellated cells 
are surrounded by the granular cells, “ so that the ciliated external layer 
of the larva represents the gastral layer of the adult, while the inner 
mass becomes the dermal layer ; the reverse of what was supposed by 
Metschinkoff and Schmidt.” In Ascetta (. Leucosolenia ) cerebrum the pro- 
cess is similar to that in Ascandra ( Leucosolenia ) variabilis. The larva of 
Ascandra variabilis is intermediate between that of A scandra reticulum 
and Sycandra raphanus. The primitive larva in Asconid phylogeny was 
probably a blastula composod of indifferent flagellated cells. The collar 
colls of the adult are derived directly from the primitive flagellated cells 
of the blastula. The larva of Ascandra variabilis fixes itself in a much 
earlier stage of development than the larva of Sycandra raphanus. The 
apparently very different Sycandra larva may be supposed to have been 
evolved from the Ascandra larva by the hastening of the process of 
development. 
According to Buck (11), the larva of Ephydatia mulleri is T5 mm. 
long, and swarms [in the aquarium] only a very short time. 
SoukAtschoff (48) found ovoid larvae, with long spined spicules, in a 
specimeu of Lubomirskia. 
According to Weltner (55) the larva of Ephydatia, jluviatilis already 
possesses irregularly disposed diactine spicules in a very early stage of 
its development. The spermatozoa of this species have a spherical head, 
with a bright, shining corpuscle, and a long flagellum. 
h. Physiology (11, 33, 55). 
Masterman (33) repeats his statements concerning the transformation 
of collar cells, after ingestion, into amoeboid cells, which sink into the 
interstitial layer, and, after having traversed it, pass through the ecto- 
derm to the exterior, carrying with them the egestive residua. In a 
similar way the cells producing spicules wander outwards, and are, 
together with the spicules they contain, ejected. Thus all these elements 
behave like the sexual cells. The Recorder feels it incumbent on him to 
state that these statements are directly contradicted by a number of well- 
known facts. 
Weltner (55) fed specimens of Ephydatia Jluviatilis with carmine 
powder. In a few hours they had absorbed all the pigment in the water 
and then appeared deep red. Kept in a greater volume of water, they 
ejected all the carmine particles in the course of a few days, and then 
again appeared colourless. 
i. Habits, Bionomics ( 3 , 4 , 7 , 11 , 32 , 34 , 35 , 55 ). 
Minchin (35) states that the larva of Ascandra variabilis swims on 
birth at once upwards to the surface, and for about twenty-four hours 
moves about near the surface. It then descends, swims for another 
twelve to twenty-four hours at lower levels, and finally affixes itself. The 
metamorphosis is completed in a few hours. The larvae of Ascetta cere- 
brum and Ascandra reticulum swim for about twenty-four hours before 
they affix themselves, whilst the larva of the British Ascetta coriacea , 
a Sponge living between tidemarks, affixes itself much sooner, already 
