XVII. SPONGIN. 
12 Spong . 
Concentrated mineral acids drive out the iodine in violet vapours, which 
condense in the shape of pure iodine crystals. Diluted mineral acids 
produoe hydrojodic acid and other volatile iodine compounds. Warm 
alkalies dissolve the Spongin. Neutralized, or after treatment with con- 
centrated nitric acid, all the iodine may be precipitated with nitrate of 
silver. The silver prsecipitats is iu great part soluble in dilute nitric acid. 
It appears that some of the iodine is lost by a process of natural 
fermentation and escapes in the shape of volatile compounds. This 
accounts for the smaller quantities of iodine in the more macerated 
specimens [and — as the Recorder would like to add — probably also for 
the peculiar smell of organic drift on the beach]. By the decomposition 
of this iodine Spongin there is produced, besides glycocoll and leucin — 
which are contained in the decomposition products of ordinary 
Spongin — also tyrosin, which is absent from the latter. Although 
unable to ascertain in what combination the iodine is contained in these 
Sponges, he believes himself justified in supposing that “es miissten 
jodirte Amidosaueren vorliegen und zwar Iodamidofettsaueren oder 
Iodtyrosine oder beide zugleich. ,, According to the chemical differences 
of the different kinds of Spongin, H. proposes the terms Iodospongin, 
Ohlorospongin, and Bromospongin. II. thinks that if those iodine- 
Spongesconld be procured in sufficient quantities they would forma most 
valuable material from which iodine could be manufactured. 
i. Habits, Bionomics (5, 11, 50). 
Oka (50) found Syllis ramosa living symbiotically in Crater omorpha 
meyeri. 
Bidder (5) says that the specimens of Leucandra aspera growing in 
impure water “ throw out a fur of fine spicules,” and it has occurred to 
him “ that this may be a filter against bacteria.” 
Bock (11) observed on Spongilla fragilis (Leidy), kept in an aquarium, 
repeated positive and negative growth, the Sponge waxing and waning 
alternately during the year and a half the observation lasted. The water 
current observed at the osculum was strong enough to carry small bodies 
to a distance of 5 cm. from the Sponge. The fresh specimens in the 
Bodensee^ are flesh-coloured, in the aquarium they became yellow. 
Similar observations were made on Ephydatia miilleri , Lieberkiihn. 
Small fragments of this Sponge are able to live and grow. Nine days 
after the gemmulae were placed in the aquarium the young Sponges crept 
out of them, and a fortnight later they began to develop Oscula. Con- 
crescence of young Sponges growing near each other was frequently 
observed. Very detailed accounts of the rate of growth are given. The 
best food for Spongilluhe is, according to Buck, water in which salad has 
been decaying ; such water is full of Infusoria. The author gives an 
account of the sexuality of Spongillidce , and states that, according to his 
experience, they do not, as other authors have supposed, die when their 
sexual products mature, or when they have produced gemmulae. He has 
