304 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



(2) the absence of anterior yellow pigment cells in the inner zone ;. and 



(3) a peculiar physical conformation of the connective tissue cells in this 

 area. A parallel fibrillation of cells acts as a diffusion grating and 

 causes light to be reflected from the anterior surface of the iris at a 

 certain ansrle as blue in colour. J. A. T. 



Transplanting Cerebral Hemispheres of Amblystoma Larvse. — 

 H. Saxton Burr {Jouni. Exper. Zool, 1920, 30, 159-69, 9 figs.). The 

 cerebral hemisphere and nasal placode were transplanted to other places, 

 especially the region just posterior to the right limb. In every case the 

 transplants showed a healthy development. The successful results of 

 the transplantation of the cerebral hemispheres show that the factor 

 which stimulates the growth phase of nervous development is not the 

 functional activity of the end organ, but the ingrowth of peripheral 

 neurones. In the transplanted hemisphere, the central grey matter is 

 restricted, particularly in the regions of the nucleus medianus septi and 

 in the primordium hippocampi. The absence of ascending fibres 

 reduces the size of the lateral forebrain tract and practically prevents the 

 formation of the columna f ornicis and the fimbria complex. A vascular 

 pia mater is formed about the transplanted hemisphere, and a choroid 

 plexus may be formed from properly placed blood vessels. J. A. T. 



Regulation in Anuran Embryos with Spina Bifida Defect. — 

 H. V. Wilson and Blackwell Markham {Journ. Exper. Zoo!., 192o, 

 30, 171-88, 5 figs.). In fishes and amphibians it frecpiently happens 

 that something interferes with the normal movement of the blastopore 

 lip over the yolk. In these cases the anterior end of the axial body 

 develops in front of the blastopore lip and is continuous behind with 

 the two halves of the latter. The authors studied embryos of Bufo 

 and Chorophilus in which blastopore closure was inhibited, and they 

 observed an interesting regulatory process. Instead of the two lateral 

 blastopore lips fusing in the midline, the blastopore is shifted over 

 toward one side, and from a single lip a backward extension of the 

 axial organs is produced. Such a tadpole was reared to a stage in which 

 external gills had been absorbed, and internal gills and opercular cavity 

 formed. J. A. T. 



Effect of Starving Young Rats.— C. ]\I. Jackson and V. A. 

 Stewart {Journ. Exper. Zool, 1920, 30, 97-127, 5 charts). Albino 

 rats fully re-fed after underfeeding from birth to three, six or ten 

 weeks, or from three weeks to nearly a year of age, grow variably, but 

 usually fail to reach the normal adult size. The ultimate effect varies 

 according to the length of the underfeeding period, the age at which 

 inanition occurred, the sex (body weight more affected in males), the 

 severity and th(; cliaracter of the inanition. The effects on particular 

 systems and individual organs are noted. Thus the ovaries are markedly 

 under weight, which probably accounts for the reduction of reproduc- 

 tive capacity marked after long underfeeding. But the abnormalities of 

 weight are usually slight, and in general it may be said that the organs 



