506 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the Metazoan digestive system is elaborated. He then passes to egestion, 
from diffuse monocytic to localised monocytic, and from egestion by 
ek-pliorocytes in simple Metazoa (sponges, Echinoderma, &c.) to greater 
specialisation in the formation of the proctodeum and nephridia. It is 
suggested that “ gonocytes and ek-phorocytes belong primitively to 
the same layer (ingestive area), both phylogenetically and ontogeneti- 
cally, the one charged with reserve material, the other 'with digestive 
residue, and that their subsequent course through the organism is 
similar.” 
Mr. Masterman gives reasons for holding that the nephrostomes are 
originally egestive in function and not excretory, and “ upon this 
hypothesis can be explained the separate ontogeny of the nephrostome 
from the mesoblast, and its intimate connection with the gonocytic 
function.” He then proceeds to discuss the evolution of strictly 
excretory function and structures. 
Index to the Journal (Zoology) of the Linnean Society.* — Zoolo- 
gists at large, as well or perhaps even more than the Linnean Society, 
are to be congratulated on the appearance of this general index to the 
first twenty volumes of the Zoological part of the Journal of this dis- 
tinguished Society. Nothing renders the publications of a learned body 
of greater value than the indexing of their publications from time to 
time. 
Tunicata. 
Development of Salpa.f — Prof. A. Korotneff has studied the develop- 
ment of Salpa cordiformis-zonaria and S. muscidosa-punctata, two forms 
belonging to different types, but with this in common, that their embryos 
are not quite hidden in their maternal tissues, as in S. costata and 
S. bicaudcita, but project freely into the interior of the respiratory cavity. 
The first-named species shows no enveloping fold ( Faltenhulle ), and thus 
belongs to the S. democratica-mucronata group, while the second is a 
“ thecogonous” form like S. maxima and S. fusiformis. 
(1) Salpa cordiformis-zonaria . The ovary consists of several ova, 
each of which becomes an embryo, beginning its development on the 
course of the oviduct. Korotneff briefly describes the unfertilised ovum, 
the polar bodies, the follicular wall, the early cleavages, the multiplica- 
tion of the follicle- cells (kalymmocytes) and their penetration into the 
follicular cavity and among the blastomeres. 
The blastomeres give rise to formative blastocytes and nutritive cells ; 
the blastocytes give rise to histogens which form the tissues ; and the 
kalymmocytes degenerate. The future ectoderm is formed by a migra- 
tion of small histogens through the wall of the follicle into the tunic- 
substance, where they form a continuous layer beneath the epithelium 
of the respiratory cavity. 
A new generation of kalymmocytes fills up the follicular cavity ; 
the cloaca and respiratory cavity of the embryo become distinguishable ; 
and the future “ placenta ” is formed as a differentiation of follicular 
epithelium, embryonic ectoderm, and that protrusion of the follicular 
wall which is known as Blutknospe. In this species the placenta is 
* London, 1896, 8vo, 437 pp. 
f MT. Zool. Stat. Neapel, xii. (1896) pp. 331-52 (3 pis.). 
