758 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the sex-substances, then the Inter determination of the other sex is pre- 

 pared for (" pre-indnction by ' hindrance of maturation ' "). 



Induction and pre-induction of sex can be brought about by external 

 influences, but only if the internal conditions of maturation and activa- 

 tion are approximately the same for the two sex-substances. These 

 conditions, however, are subject to autonomous fluctuations. The male 

 and female substances may vary periodically in being equivalent, pre- 

 valent, or recessive as regards one another. If we adopt the author's 

 suggestion of applying the ideas of the ferment and antigen theory to 

 these substances and processes, we can suppose that the alternating 

 appearance and suppression of inhibiting substances (" paralysators "), 

 or of activating substances ("activators"), are the real causes of the 

 periodicity of sex-determination, The sex-substances themselves may 

 be considered as somewhat like pro-ferments (if latent), and ferments 

 (if activated). 



Annulata. 



Structure of Tomopteris.* — Jakob Nanni gives an histological ac- 

 count of the nervous system, the food canal, the vascular system, the 

 musculature, and the eyes of various species of this interesting genus. 



Incubation in Polychaets.t — Ch. Gravier describes from the collec- 

 tion of the second French Antarctic Expedition two interesting forms of 

 incubatory Polychaets. The first is Parautolytus fasciatus, which secretes 

 a veil on the dorsal surface, forming a pouch for the eggs and larvae. 

 The second is a new species of Eteone, which occurred rolled round its 

 spawn. The relatively large ova form a compact block fixed to the sides 

 and ventral surface of the Annelid, and enveloped by a brown membrane. 



Irish Maldanidae.J — Ivar Arwidsson describes from the Irish coasts, 

 Nicomache maculata sp.n., and establishes a new genus, Csesicirrus, for 

 G. neglectus nom n. (= Axiothea catenata (Malmgren) Cunningham and 

 Ramage). The most distinctive characters of the genus are the appear- 

 ance of the eighth setigerous segment, the division of the anal cirri into 

 long undivided ones and short ones lobate at the point, and the pro- 

 longed anal papilla. The nephridial pore is somewhat under the rows 

 of uncini, and in a line with or slightly in front of these. The neck of 

 the developed uncini is a little striated in an oblique fashion. 



Littoral Oligochaeta of the Clyde.§ — J. Stephenson makes a con- 

 tribution to our knowledge of the littoral Oligochaata. He collected in 

 the vicinity of Millport Marine Biological Station and at Wemyss Bay. 

 Ten species are dealt with, all Enchytrasids except Tubifex costatus. 

 Two new species of Lumbricillus and two of Enchytrmis are described. 

 The author points out that these two genera are closely allied, and that 

 a number of intermediate forms exist which serve to bridge over the 

 interval between them. 



* Jen. Zeitschr. Natur., xlvii. (1911) pp. 343-66 (2 pis. and 2 figs.), 

 t Comptes Hendus, clii. (1911) pp. 1418-20. 



; Vroc. li. Irish Acad., xxix. (1911) Section B, No. 6, pp. 209-28 (3 pis.). 

 § Trans. R. Soc. Edinburgh, xlviii. (1911) pp. 31-65 (2 pis.). 



