716 SUMMARY OF CURRENT RESEARCHES RELATING TO 



metbylene-grccn ftiid picrocarniiuc are to bo preferred. The best way to 

 fix the cells is to place the organ for some time in a saturated solution 

 of acetic and picric acids. 



Anatomy and Histology of Limax agrestis.*— Dr. E. Hanitscb has 

 a contribution to the knowledge of the Slug. He is of opinion that tho 

 chief ixirt of the movement of the radula is due to the extrinsic muscles. 

 The roof of the mouth is provided with a jaw, the epithelium of which 

 rests in a layer of muscle-fibres which run in longitudinal, tratisverse, 

 and dorsovcntral directions, and seem to enable this upper jaw to move 

 freely in various directions. The epithelium of the kidney, unlike that 

 of the LamoUibranchs and Nudibranchs, is not ciliated. The lobes of 

 Semper's organ were found to be masses of pyriform glandular cells, 

 arranged in the form of a bouquet ; the pointed ends of the pyriform 

 cells lie anteriorly, and the ends of the individual cells are continued 

 into long canals of very small diameter, which lead to a papilla placed 

 immodiaiely above ; each canal seems to open separately to the exterior. 



The pedal gland has been lately investigated by Dr. Szekely who 

 describes its opening as being elliptical in transverse section ; further 

 back the lumen has the form of a fungus, and the posterior part is 

 flattened and lanceolate. The floor of the duct is raised into two 

 longitudinal folds, which are separated in the median line by a slight 

 depression ; these folds and depression are covered by ciliated epi- 

 thelium ; glandular cells are numerous on the ventral and lateral 

 portions of the duet. The fine fibres which form a network at the base 

 of the ciliated cells are regarded by Szekely as connective tissue, and 

 not nervous, and he comes to the conclusion that the pedal gland is not 

 a sense-organ, but simply a secretory gland which furnishes the mucus 

 necessary for creeping. Dr. Hanitsch agrees generally with the 

 Hungarian anatomist, but he found elongated and pointed cells of 

 apparently a sensory nature, and so numerous tliat he cannot accept 

 Szekely's explanation of Sochaczewer's observation, that they were 

 accidental products. Numerous ganglion-cells were found lying beneath 

 them, but he has not yet been able to trace nerve-fibres from one to the 

 other. What Soehaczewer took for nerve-fibres wcrr probably fibres of 

 the connective tissue from tho capsules which inclose the gangliou- 

 cells. 



Anatomy and Histology of Cyclostoma elegans.f — M. P. Garnault 

 has made a detailed study of the anatomy and histology of Cyclostoma 

 elegans. He begins with describing the crystalline structure of the 

 shell. The alimentary system is then discussed ; the stomach is clothed 

 by a cuticle pierced with minute canals ; all the i)arts of the canal have 

 an alkaline reaction. In regard to the vascular system, he denies the 

 existence of a clothing endothelium on the walls of the lacunae, and 

 regards the afferent veins as narrowed lacunas. The venous network of 

 the mantle is described. Sections of the superior region compared with 

 the same in Bithynia tentaculata show that Cyclostoma has a rudimentary 

 gill in process of disai)pearance. Analyses of the contents of the 

 respiratory cavity demonstrated, even with the animal inclosed in its 

 shell, the occurrence of gaseous interchange with the exterior. 



The glandular lamellae and very complex arrangement of the 



♦ Proc. Biol. Soc. Liverpool, ii. (1888) pp. 152-70 (3 pis.), 

 t ActesSoc. Liuu. Bordeaux, 1887, pp. 1-152 (9 pis). 



