932 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Organ of Verrill in Loligo.* — Mr. M. Laurie has discovered in a 

 young LoJiifo about 6 mm. in length an organ which appears to be homo- 

 logous with the valve-like organ described by Verrill at the base of the 

 siphon in Dcsmateiithis and Taonia. It consists of a median dorsal 

 cushion, which is prolonged backwards with two largo processes, and a 

 pair of lateral cushions on the ventral wall of the siphon. The organ 

 is glandular in structure. It is well developed in si>ecimen8 of Omma- 

 strephes about 8 mm. long, but there is no trace of it in adults of that 

 genus or of Lolhjo ; it is probably, therefore, an archaic organ, but cannot 

 bo compared with anything known in Gastropods. 



Salivary Glands of Sepia officinalis and Patella vulgata.f — Dr. A. 

 B. Griffiths has found that the salivary secretion of the cuttle-fish con- 

 verts starch into glucose ; mucin, sulphocyanates, and what seemed to 

 be phosphate of calcium were found in the salivary secretion. Similar 

 results were obtained with the limpet. The subjoined table gives a 

 resume of tlie author's already attained results. 



The salivary glands of these molluscs seem to have the same func- 

 tions as those of Vertebrates. 



y. Gastropoda. 



Spermatogenesis 'of Gastropods.^ — Dr. A. Prenant describes the 

 Fpcrmatogeucsis of Palmonate Gastropods (Jlclix, Avion), and draws 

 the following principal conclusions. (1) The resting spermatogonium 

 includes peculiar cjtomicx'osomata, which are the rudiments of tho 

 " Nebenkcrn," or it may contain the perfect Nebenkern itself. It may also 

 exhibit other structures, described by Platner in Lepidoptera as well 

 as Gastropods, and regarded by him as distinct from the Nebenkern. 



(2) In division the initial phase of the karyokinesis exhibits a remarkable 

 mode of " pelotonnement " and transverse fission, as Platner observed, 

 though Prenant's details diflter from those of the previous investigator. 



(3) The Nebenkcrn appears to the author to develope indirectly, not 

 directly, from the spindle. Vestiges of the spindle form special 

 cytomicrosomata, which give rise to the Nebenkern. 



(4) In the spermatides, the Nebenkern takes part along with the 

 protoplasm in forming the spiral filaments of the envelope of the axial 

 filament. The long caudal filament described by Platner as the head- 

 piece, seems to the author to result from the median portion. The axial 

 filament is formed in its anterior portion of two or more superposed 

 knobs, as Jensen has described in mammals. The differentiation of the 

 epermatide nucleus is described at length. 



* Quart. Joum. Micr. Sci., xxix. (1888) pp. 07-8 (1 pi.), 

 t Proc. Roy. Soc., xliv. (1888) pp. 327-8. 

 X La Cellule, iv. (1888) pp. 137-77 (2 pis). 



