406 



SCIENCE. 



[Vol. I., No. 14. 



Multiplication of ■worms by division. — Dr. C. 



Billow has investigated the processes of transverse 

 division in Lumbriculus variegatus, and tlie regen- 

 eration of parts to complete a new individual out of 

 the pieces of the parent body. His article is prefaced 

 by a valuable resume of previous investigations. In 

 Lumbriculus, besides the sexual there is a natural 

 asexual propagation, by simple transverse division, oc- 

 curring spontaneously. Head and tail, botli or either, 

 can be re-formed. There is no budding zone formed 

 before division: the process is therefore different 

 from that in Nais and the Syllidae. In both head and 

 tail the segments are apparently newly developed 

 from before backwards {contra Bonnet). The head 

 and tail buds are formed witliin 48 hours after divis- 

 ion; and, in a few days, defecation through tlie new 

 tail-end may be observed. The re-development may 

 be produced by artificial division. One individual 

 was cut into fourteen pieces, of which thirteen grew 

 up to complete individuals. (The paper would have 

 been improved by much shortening and more careful 

 arrangement.) — (Arch. fiir. naturgesch., 1883, 1.) 

 c. s. M. [845 



Anatomy of Prorhynchus. — J. von Kennel pub- 

 lishes an article on Prorhynchus, one of those doubt- 

 ful genera of worms whose systematic positien could 

 not hitherto be satisfactorily determined. Kennel 

 shows definitely that it is a rhabdocoelus turbellarian. 

 It has a simple straight intestine, and muscular phar- 

 ynx. The structure of the integument and paren- 

 chyma of the body is like that in other Khabdocoela, 

 and not like that of nemerteans. The same may be 

 said of the nervous system. The penis lies well for- 

 ward, and, before its structure and relations were 

 correctly understood, was compared to llie proboscis 

 of nemerteans, with wliich it has no relation. It is 

 armed with a spine, and has a muscular bulb at its 

 base, which is ■ connected by a somewhat tortuous 

 duct with the vesicula, in which the products of tlie 

 male glands are directly received. It lies veutrally 

 from the pharynx. The stylet is exserted through the 

 mouth. It is a very complicated apparatus, which tlie 

 author fully describes. There are no separate yolk- 

 glands; but these are united (unlike other plathel- 

 minths) in one mass witli the ovary. This is the 

 most important difference found between Prorhyn- 

 chus and other Khabdocoela. — {Semper' .i arheiten, 

 vi. 69.) c. s. M. [846 



VERTEBRATES. 

 Equilibration functions of the semicircular 

 canals. — From observations on dogs witli one or 

 both auditory nerves divided, Bechterew concludes: 

 1°. Unilateral section is followed by forced move- 

 ments of rotation around the long axis of the body, 

 with deviation of the eyes, nystagmus, etc. 2°. The 

 movements, at first constant, occur later in parox- 

 ysms separated by periods of rest. During the latter, 

 the animal assumes a constrained position, lying on 

 the opposite side to tliat of the section. Finally, the 

 rolling movements altogether cease; but the animal 

 has a tendency to exhibit circus movements towards 

 the injured side, and has a deficient power of main- 

 taining its balance on its feet. 3°. All the above 

 symptoms are reflex, since they are still exhibited 

 after removal of the cerebral hemispheres, or in nar- 

 cosis. They are, however, more marked when the 

 hemispheres are present. 4°. Section of both audi- 

 tory nerves is accompanied by marked deficiency of 

 the power of maintaining equilibrium. The animal 

 can neither stand nor walk. 5°. When only one 

 nerve is cut, tlie forced movements are due to a dis- 

 liarmony resulting from the absence on one side of 



the normal semicircular-canal sensations, and their 

 presence on the other. Hence the cerebellar equili- 

 bration-centres act abnormally; also, when the cere- 

 brum is present, tlie uninjured side sends stimuli to 

 the centres of consciousness, which, being unbalanced 

 by the usual associated stimuli from the other side, 

 lead to vertigo. 6°. The well-known action of audi- 

 tory impressions in influencing movements (as in 

 dancing and marching) occurs, in all probability, 

 tlirough the semicircular canals. — {Pfliig. archiv, 

 XXX. 312.) H. N. M. [847 



Influence of the spleen on pancreatic diges- 

 tion. — Twenty years ago SchifE jiublished researches 

 which led him to believe, that, after removal of the 

 spleen, the pancreatic secretion lost its power of di- 

 gesting proteids. His final conclusion was that, the 

 spleen did not itself make the proteolytic ferment, 

 but furnished to the blood something essential for its 

 formation in the pancreas. Schifi's statement at- 

 tracted but few adherents; and Haidenhain, in 1875, 

 proved that a substance (zymogen) capable of yield- 

 ing proteolytic ferment, accumulated in the pancreas 

 quite independently of the presence or absence of 

 the spleen. This seemed, at first sight, to completely 

 overthrow Schiff's theory of the splenic function iii 

 digestion. Herzen now, brings forward experiments 

 wliieh reconcile tlie apparently opposite conclusions. 

 He claims that his researches on dogs prove that 

 after removal of the spleen, the pancreas may still 

 heap up zymogen {trypsor/en), but that this is not 

 iinder such circumstances transformed into a pro- 

 teolytic ferment (trypsin), as it is normally when 

 the spleen is present and in physiological activity. 

 Hence, after splenotomy, or in cases of serious splen- 

 ic disease, the digestion of albuminous substances 

 is greatly impaired. — {Pfldij. archiv, xxx. 295.) 



H. N. M. ' [848 



Mammals. 

 Early stages of the guinea-pig ovum. — Spee 

 has published the results of his observations on this 

 subject. Up to the beginning or middle of the 

 fourth day, the ova remain in the oviduct, whence 

 tliey must be carefully extracted. Eggs of two days 

 liave four segmentation-spheres, around and between 

 which a coagulated mass soon appears po.st mortem. 

 On the third day the limits of the cells are unrecog- 

 nizable ; but tliey may be more or less isolated by 

 bursting the ovum. After the fifth day, the coagu- 

 lum no longer appears around the segmentation- 

 spheres. In all the early stages post-mortem changes 

 are very great and rapid. While still free, after the 

 fourtli day, the ova lie in the tip of the uterus, 

 whence they may be driven by forcing with a syringe 

 a current of warm 0.5% salt solution into tlie vagina, 

 and out of the tip of the uterus (after cutting off the 

 oviduct). By employing this method, Spee has ob- 

 tained germ-vesicles (keimblasen) agreeing essen- 

 tially with corresponding stages as found in other 

 mammalia, the principal difference being that the 

 cells are relatively larger, segmentation not liaving 

 progressed so far. There is an outer wall close against 

 the zona pellucida, and composed of a single layer of 

 cells, spindle shaped when seen in section, polygonal 

 when viewed from the surface. At one pole is an_ 

 accumulation of cells, the " keimhiigel,' while at" 

 the opposite pole the cells at the outer layer are thick- 

 ened. In a later stage the cells of the latter pole 

 are found to have thrown out branching processes 

 which penetrate the zona pellucida. Apparently 

 these processes increase in size; and it is probable that 

 they maliC a hole through the zona by which the egg 

 makes its exit. Spee has actually found, in one case. 



