70 SUMMARY OF CUERENT RESEARCHES RELATING TO 



limits of the species : thus Hydatina has thirteen cells in its cingulum 

 and Stephanoceros has the same number. 



Echinoderma.. 



Observations on Labidoplax buskii.*— S. Becher adds some ob- 

 servations to Ostergren's description of this Synaptid, which is common 

 on the west coast of Sweden. He has discovered the presence of a 

 definite closable abdominal pore in an inter-radius near the posterior end, 

 or of several pores in several inter-radii. Migrant amoeboid cells pass 

 out by the pore, which may also be of use in respiration. In some vivi- 

 parous forms such ii pore, if present, may serve for the emergence of the 

 larvse. Becher also describes the occurrence of stalked sensory buds on 

 the body-wall, and notes their predominantly bilateral arrangement. 

 A^nother noteworthy fact is the orientation of anchors and plates in close 

 relation to the five main nerve-strands — an arrangement which is shown 

 to be useful in locomotion. On the oral surface of the eleven tentacles 

 the current is always towards the base, on the outer surface towards the 

 tip. The author also discusses the contractile rosettes or pulsatory peri- 

 toneal vesicles, and the minute structure of various organs. 



Study of Asteronyx loveni.f — Th. Mortensen describes in the first 

 place a young stage. The most striking features are the large disk- 

 plate, the typically developed ventrals, the large terminals, and the 

 unusual expansion of the lateral oral shields. The interest of this is 

 particularly in the primitive character of the larval feature as compared 

 with those of the adult. In regard to the general occurrence of Aster- 

 onyx loveni on large Pennatulids, notably on Funiculina quadr angular is, 

 it is suggested that it gets it food best in this way, and is also protected 

 by the association. The ova of Asteronyx are of considerable size 

 and with a considerable quantity of yolk ; they do not develop in the 

 bursfB, which are not big enough for that ; but it is unlikely that there 

 is a typical ophiopluteus. A remarkable parasitic Copepod occurs in the 

 gonads. The remarkable discontinuous distribution is discussed. 



Coelentera. 



Experiments on Ctenophore Ova. J — Naohide Yatsu has worked with 

 Beroe ovata, B. forsJcalii, Calliamra bialata, and Eucharis multicornis, 

 especially with the first. The a^g consists of the outer homogeneous 

 layer, the ectoplasm, and the endoplasm. The outer layer corresponds 

 to Ziegler's " hyaline outer layer " in the Echinoderm egg. The ecto- 

 plasm is an alveolar plasm, and rays may be formed on it. It is 

 phosphorescent. The sperm-rays and pole-rays of the first division 

 enter the endoplasm, the alveolar walls taking a radial arrangement. 



Polyspermic eggs may cleave normally. Cleavage is not strictly 

 unilateral, the furrow being formed in the micromere region. Fine 

 spinning of the homogeneous layer can be seen at the entrance and at 



* Zeitschr. wiss. Zool., c. (1912) pp. 290-324 (1 pi. and 5 figs.). 



t Zeitschr. wiss. Zool., c. (1912) pp. 264-89 (5 pis.). 



X Journ. Coll. Sci. Univ. Tokyo, xxxii. (1912) pp. 1-21 (5 pis.). 



