212 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



SUMMARY 



OP CURRENT RESEARCHES RELATING TO 



ZOOLOGY AND BOTANY 



{principally Invertchrata and Cryptogamia), 



MICROSCOPY, &c., 



INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS* 



ZOOLOGY. 



A. GENERAL, including Embryology and Histology 

 of the Vertebrata. 



Development of the Heart in Vertebrates and Invertebrates.! 

 — "W. Schimkewitscli's observations upon this subject show that the 

 heart of vertebrates and invertebrates does not develope either from 

 the somatojileure or splanchnoi)leure, but in a region corresponding 

 to the dorsal mesentery of worms. The separation of the heart-cavity 

 from the lumen of the mid-gut is only apparent in invertebrates ; it 

 is actually a remnant of the segmentation cavity in both vertebrates 

 and invertebrates. The origin of the vertebrate heart from two 

 separate cavities is in spite of Balfour's assertions a primitive mode of 

 development. 



Embryology of Lacerta viridis.| — An earlier research of H. Strahl 

 upon this subject has already been noticed.§ The results of additional 

 observations mainly upon the neurenteric canal and associated struc- 

 tures are as follows : — After the invagination which forms the neuren- 

 teric canal the latter is found to be contained within a mass of cells, in 

 contact above with the medullary plate and covered below by a thin 

 layer of endoderm, which is mesodermic ; in front the walls of the 

 canal are continued on as a narrow cord without a lumen, which is 

 accompanied moreover by no endoderm layer ; in a later stage the 

 canal acquires its internal opening behind, which in this and all sub- 

 sequent stages is covered by a definite layer of endoderm ; anteriorly 

 the canal appears to rest directly upon the yolk ; it is not covered by 

 endoderm, but appears to be accompanied by a band of endoderm in 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, or for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actualhj published, 

 and to describe and illustrate Instruments, Apparatus, &c., which are either new 

 or have not been previously described in this country. 



•f- Zool. Anzeig., viii. (188.5) pp. 37-40 (4 figs.). 



X Abh. Senck. Naturf. Gesell., xiii. (1884) pp. 409-71 (5 pis.). 



§ See this Journal, iv. (1884) p. 361. 



