ZOOLOGY AND BOTANY, MI0EO8COPY, ETC. 103 



consist of an organic substance and are reserve material. (6) The pigment 

 also occurs in the reproducing forms, is never diffuse but always granular, 

 varies from blue to reddish violet, and appears simultaneously with the 

 crystals. They are excretory masses, formed during the spore-building, 

 and are left behind. Their chemical reactions are noted in detail. (7) The 

 connecting jelly-like substance is normally present and is of great importance 

 in keeping the colony together. It increases throughout the vegetative 

 period both in mass and consistence, and becomes sometimes almost car- 

 tilaginous. It disappears rapidly in confined specimens. After the ap- 

 pearance of the zoospores it also decreases, first slowly and then rapidly. 

 Even in dead spirit specimens some physical properties, e. g. of swelling 

 out again in water, remain. Morphologically this substance is an excretion 

 of the protoplasm. Physiologically, it is essential to the connectedness, 

 protection, hydrostatic and even nutritive functions of the colony. (8) 

 Vacuoles are not present in very young colonies. As the jelly-like sub- 

 stance becomes separated from the penetrating fluid, vacuoles are formed, to 

 disappear again as spore-formation begins. They are surrounded by a fine 

 plasmic layer. The variations in form and distribution are noted. The 

 author regards them as entirely comparable to the vacuoles of other Pro- 

 tozoa. (9) The sheleton. The presence or absence of a skeleton cannot be 

 regarded as establishing a natural division. In noting the mode of growth 

 Brandt maintains the existence of an organic basis with subsequent silicifi- 

 cation. He deprecates the erection of species on the variations of the 

 spicules. (10) Telloio cells. These symbions, which Brandt has named 

 Zooxanthella, are regarded as perhaps allied to the PeridineEe. The results 

 of assimilation are starch-grains and also granules of different composition. 

 Their presence at different periods, their behaviour when isolated, and 

 other points are then noted. (11) Individuality of colonies. Colonies of 

 different species cannot fuse, but colonies of the same species may, and that 

 independent of the developmental stages of the two fusing forms. As 

 Schneider has shown, artificial division is readily practicable. There is 

 more division of labour within the colony than Hertwig allowed. The 

 functions of intra- and extra-capsular protoplasm are quite distinct. The 

 central capsule even, which solely forms the spores, is not homogeneous in 

 its functions. 



II. Biology. — (1) Nutrition. After noting general facts as to food 

 material, Brandt emphasizes the truly nutritive function of the symbiotic 

 algse, which contribute the results of their assimilation (starch, &c.) to their 

 animal host. The breaking up of these " yellow cells " during swarm- 

 formation is specially noted, and also the changes in the assimilative 

 protoplasm. (2) Movement. The plasmic portions being much heavier than 

 sea-water are floated by the vacuoles and by the gallert-substance, which 

 sometimes appear to-be lighter than sea-water, and enormously increase 

 the surface. Mechanical and thermal stimuli produce changes which effect 

 sinking and rising. The pseudopodia affect the specific gravity through 

 their influence on the vacuoles. (3) Occurrence of different forms. The 

 distribution of ten species is described in detail, and graphically expressed 

 in curves. The principal result shows their varied occurrence at different 

 seasons. (4) Environment, (a) The Sphgerozoa are very sensitive to changes 

 of salinity, (b) They are uninfluenced by light. Even extreme illumi- 

 nation does not affect their vertical distribution. The statement of Geddes 

 that Eadiolarians move from the light is denied, (c) Apart from seasonal 

 changes, alterations of temperature do not appear to have much effect upon 

 these forms. On gradual cooling several forms were observed to sink. 

 Two forms withstood a prolonged cooling to 1°, but exhibited changes 



