SUBJECT-INDEX. 
Tun. 5 
c. Embryology. 
Metcalf shows that in different species of Ascidians the ganglionated 
dorsal nerve cord of the embryo may arise from the cellular cortex of the 
brain, from the neural gland, or from a mass of cells formed by the fusion 
of brain and gland. He shows that there is a peculiarly intimate relation 
between glandular tissue and nervous tissue in the Tunicata hardly to be 
paralleled elsewhere in the animal kingdom. 
Gaskell in his studies on the origin of Vertebrates, considers that the 
thyroid gland o'f Ammocostes has given rise on the one hand to the 
endostyle of Amphioxus and the Tunicata, and on the other to the 
thyroid of Petromyzon and the rest of the Vertebrata. Occasional other 
references to the structure of Amphioxus and the Tunicata occur in the 
paper. 
Crampton describes the stages in the formation of yolk in the egg of 
Molgula. At first there are no yolk granules. Then a small albumenous 
granular body is formed just outside the nucleus. This grows larger 
during the “period of formation of the yolk mass.” The next period is 
the “disintegration of the yolk mass”—the granules being spread through 
the vacuolated cell body. In the third period the products of disintegra¬ 
tion enlarge to form the definite deutoplasm spheres. 
Bancroft deals with the development of the sexual organs in Distaplia 
occidentalis and their structure in the adult in various species. His 
subjects are:—the incubatory pouch, the envelopes of the ovum, the 
test-cells—their origin and fate, the other follicular cells, the structure of 
the ovum and its maturation. He considers that the “ test-cells ” are 
derived from follicle cells, and that they take no part in the formation of 
the test. 
Korotneff finds in Salpa maxima-africana that the polar body is of 
exceptionally large size, equivalent to the ovum itself. Segmentation 
results in macromeres and micromeres, which however is only a temporary 
distinction. 
Golski gives some information in regard to the maturation and fertiliz¬ 
ation of Ciona intestinalis. The first polar body apparently often sub¬ 
divides to form two. 
Pizon has followed day by day the changes in a young colony of 
Botrylloides rubrum , and traces the rise of the successive generations of 
buds and the degeneration of their parents. He also makes observations 
upon the effect of light, the beating of the heart and colonial circulation, 
and the duration of life in the members of the colony. 
d. Geographical Distribution. 
Lohmann finds 26 species of Appendicularida in the Straits of Messina, 
of which 3 are new to science. 
Hartmeyer records 11 species of simple Ascidians from the Bremer 
Expedition to the East of Spitzbergen (1889). Of these 2 are new species 
and several others are new records to the fauna of Spitzbergen. 
Ritter describes 12 species of Tunicata from the Pribilof Islands of 
which 11 are new to science—3 simple and 8 compound Ascidians. 
Herdman has recorded from the Australian seas 183 species of 
Tunicata, while only about 176 species are known from the shores of 
North Western Europe. Sixtv-three of these Australian species are 
described and figured for the first time in the author’s “ Catalogue.” 
