36 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Simple Ascidians from Spitzbergen.* — Dr. Robert Hartraeyer 

 publisbes an important paper on tbe simple Ascidians collected by 

 Dr. Kiikenthal in tbe Bremer Expedition. Tbe paper is later to form part 

 of tbe article on Monascidia in Roraer and Schaudinn's ' Fauna arctica,' 

 and contains many anatomical details, an account of tbe distribution of 

 tbe forms discussed, and full literature lists. An interesting point is 

 tbe erection of a new species (C. arctica) for tbe Arctic Cynthia hitherto 

 included under Q. ecMnata. 



Vascular Ampullae in Botryllidse.f — Mr. F. W. Bancroft has studied 

 tbe function of tbe terminal enlargements or ampullae which occur on the 

 (ectodermic) colonial vessels of tbe Botryllidse. They are found nearly 

 everywhere within the colony, but are situated principally along the 

 edges, which they often line several rows deep. Some zoologists still 

 hold that these ampullae may form buds, but most consider them as 

 reservoirs for blood, as organs for the secretion of tbe test matrix, and 

 as belping in respiration. Bancroft finds that in tbese three respects 

 the ampullae perform important functions, but he adds another to the 

 list of their activities, — namely, that of blood propulsion. 



In Botryllus and Botrylloides they normally execute co-ordinated 

 pulsations ; tbese pulsations continue after separation from the rest of 

 the colony, but the nature of the co-ordination changes. In the various 

 zooids tbe hearts do not beat in time ; tbe rhythm of tbe ampullar 

 pulsations is not affected by the reversals of the hearts of tlie zooids. 

 Tbe pulsations are very slow, tbe systole averaging 38 seconds and the 

 diastole 33 ; tbe contracting tissue is a tbin pavement epithelium. The 

 co-ordination of tbe ampullae is accomplished principally by means of 

 variations in blood-pressure. In the aestivating colony of Botrylloides 

 gascoithe circulation is kept up almost entirely by the ampullae. 



Branchial System of Ascidians.}— Marc de Selys Longcbamps con- 

 cludes a detailed description of the branchial system of Ascidiella 

 scabroides, and considers the value of its structural peculiarity as a 

 specific character. The differences at different ages are very marked ; 

 thus it seems probable, though not certain, that A. scabroides and A. scabra 

 are one and the same species at different stages. 



INVERTEBRATA. 



Mollusca. 

 a. Cephalopoda. 



Experiments on Squid Eggs.§ — Herr W. Schimkewitsch finds that 

 extraordinary changes can be brought about in the developing ova of 

 Loligo by placing them in solutions containing sulphate of magnesium, 

 bromate of sodium, guanin, Ac. Thus, the invagination process may 

 be replaced by what is essentially delamination. The ectoderm-cells, 

 after reaching the yolk in the annular depression, may exhibit a one- 

 sided teloblastic growth ; but diagrams would be necessary to make this 

 point clear. In one case, in lithium solution, the normally invaginate 



• Zool. Jalirb. (Abt. Syst), xii. (1890) pp. 453-520 (2 pis. and 11 figs.). 



f Zool. Anzeig., xxii. (1899) pp. 450-62 (2 figs.). 



t Arch. Biol., xvi. (1899) pp. 153-71 (3 pis.). 



$ Anat, Anzeig., xvi. (1899) pp. 564-8. 



