BIOLOGY. 
Spang. 7 
Maas (25) describes the development of the ovum, and the earliest 
stages of the larva of Sycandra raphanus. The ova are specialised 
amoeboid wandering cells. An ordinary cell of this kind grows in size 
and its nucleus becomes considerably larger. The nucleus lies centrally 
and contains a nucleolus. The chromatin forms a very fine and com- 
plicated network of threads. When the ovum ripens the chromatin- 
network becomes more coarse, the single nucleolus is replaced by several, 
and the nucleus wanders towards the surface. Then the polar bodies are 
formed mitotically. One of them perhaps remains in the ovum. The 
nucleus of the spermatozoon, which now enters, has the same size as the 
nucleus of the ovum. The two nuclei join under the formation of 
Chromosomes and immediately produce the first cleavage-spindle. The 
first, second and third cleavages are meridional, the fourth is aequatorial. 
f. Physiology [cf. Titles 8, 20]. 
Delage & H:erouard (10) consider the collar-cells as the elements 
which resorb the food and which excrete the useless products. 
Lexdexfeld (20) in criticising Loisel’s statements [Zool. Eec. 1898, 
(35)] points out that anilin dyes can be taken up by any (living) cells, 
so that their absorption can be no proof of a food-resorbing function of 
such cells. 
G. Habits, Bionomics [cf. Titles 12, 13, 14, 24, 37, 47]. 
Lo Bianco (24) gives a list of the Sponges in the Bay of Xaples with 
notes on their habitats and times of producing larvae. 
Girod publishes statements concerning the mode of life of Cartenus 
bohemicus (12) and the Freshwater Sponges generally (13). 
Grayier (14) dwells on the suspension of vital functions in Freshwater 
Sponges during the dry season. 
2. GEOGRAPHICAL DISTRIBUTION. 
a. General [cf. Titles 11, 34, 42]. 
Schulze (34) compares the Hexactinellids of the Atlantic and Pacific 
American waters. Of the 9 families 7 occur in both, 2 in the Atlantic 
alone. Of the 39 genera only 9, and of the 66 species only 2, are common 
to both. In the Atlantic the Euplectellidce , Asconematidce and the more 
complicated Dictyonine forms predominate, whilst the Rossellids are 
characteristic of the Pacific. 
Concerning the depths in which American Hexactinellids have been 
found Schulze (34) states that Rhabdocalyptus dawsoni occurs in the 
shallowest (55 metres) and Caulophacus agassizii in the deepest (3235 
metres) water. 
b. Fauxistic [cf. Titles 1, 5, 9, 11, 13, 15, 19, 21, 24, 29, 32, 34, 
41, 42, 43]. 
Continent of Europe. —Girod (11, 13) gives accounts of the geographical 
distribution of the European Freshwater Sponges. 
Continent of Africa. — Evans (9) describes two species of Spongillids 
from Lake Tanganyika. 
Continent of America. —Grayier (14) describes a Freshwater Sponge 
from Venezuela. 
1899. [Vol. xxxyi.] f 6 
