( 75t) ) 

 EECORD 



OF CURRENT BESEABCHES RELATING TO 



INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, &c.* 



ZOOLOGY. 



A. GENEHAL, including Embryology and Histology 

 of the Vertebrata. 



Development of the Rabbit. t — The recent observations of Pro- 

 fessor Kulliker have shown him that on the fifth clay the area cmbryo- 

 nalis of the rabbit is made up of three layers ; these are 



(a) The cells of the investing layer of Rauber, which are flat and 

 large and are part of the primitive unilaminate germinal 

 vesicle. 



(h) A layer of flattened, pretty thick, small cells, which he (as 

 also Rauber) regard as ectodermal, while Edouard van 

 Beneden looks upon them as forming the mesoderm. 



(c) The cells of the endoderm are flat and large. 



He fiuds tbat the investing cells of Rauber are temporary struc- 

 tures wLich have no relation to the formation of the ectoderm ; this 

 is, of course, in express opposition to the view of their future which is 

 taken by Van Beneden, but it is one on which the learned German 

 embryologist speaks very confidently ; nor is this all, the mesoderm 

 is stated not to aj)pear till the time when the primitive stripe begins 

 to be formed ; when it docs begin it takes all its origin from a thicken- 

 ing of the ectoderm, and has no relations to the endoderm. 



The demonstration of the presence of a number of pieces of nuclei 

 and cells in the young embryos, and their jn-esence in number in tlio 

 structures which are undergoing conversion, seem to show that at 

 these stages the chief part is played by the growth of the cells, and 

 not by any mechanical causes. The author promises further details 

 shortly. 



Development of the " Glomerulus of the Head-Kidney" in the 

 Chick.J — This structure has been already noted by Mr. Adam Sedg- 

 wick and Mr. Balfour, and Gasser has arrived at similar conclusions 

 as to the characters of the structure. In the i)rcvious communication 

 no definite answer was given to the point as to whether this glome- 

 rulus was a " continuous structure." A study of its development lias 

 since shown Mr. Sedgwick that it is not so, but that the external 

 glomerulus or glomerillus of the head-kidney of the chick consists 



* cS^T It should lie understood tliat (he Society do not liold tliemselves respoii- 

 sihle for tlic views of the luithora of the jiapers, &e., referred to, nor for the umuner 

 in which those views may be expressed, the object of tiie Record being to present 

 II siiniiuiiry of the puj'ers 'is actttal/i/ puhlislied. Objections and corrcctious should 

 tiirrefore, for tlu- nitjst part, be addressed to the autiiors'. 



t 'Zool. Anzeig.,' iii. (I8«U) j). :J70. 



t ' Quart. Jouru. Mier. Sci.,' xx. (1880) p. 372. 



