ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 347 



communicate, by means of two or three openings, with the vein running 

 along their mesial borders. 



At the beginning of the fourth week, the mesenchymal tissue con- 

 denses about the veno-lymphatic channels to form definite walls. These 

 cardiac walls are then invaded by muscle-cells from the adjacent muscle 

 plates. 



The final stage in the development of the posterior lymph-hearts is 

 reached by the dilatation and confluence of these veno-lymphatic sinuses, 

 from before backward, forming a pair of sac-like organs, each with a 

 single central cavity. 



It appears from the investigation that the mesenchymal spaces play 

 a much greater part in the development of the lymphatics in general 

 than is usually supposed. 



Blastopore Closure in Amphibia.*— H. W. Goodale finds that it is 

 possible to make a definite relatively permanent mark with Nile blue 

 sulphate on the eggs of Spelerpes bilineatus. The dye stains the yolk- 

 granules. Among other experiments a series of spots was made about 

 the equator shortly before gastrulation. During gastrulation the spots 

 elongated into bands, which, when the blastopore is nearly closed, extend 

 from the equator to the edge of the blastopore. The extension into 

 bands is due to the division and subsequent migration of part of the 

 daughter-cells of the equatorial cells. The stained yolk-granules record 

 their path. In Spelerpes the niodle of blastopore closure is very unusual. 

 The lateral lips extend so as to cover half of a circumference, and then 

 further progress ceases. The blastopore gradually contracts into a 

 straight line, which shortens until at last only a minute median portion 

 remains as the anus. The blastopore never becomes circular, nor is 

 there a definitive ventral lip. 



Inheritance of Complex Growth-forms. f ; — J. Brownlee discusses 

 the interesting question of the inheritance of complex growth-forms, 

 such as stature, on Mendel's theory. He submits two conclusions : (1) 

 If the inheritance of stature depends upon a Mendelian mechanism, then 

 the distribution of the population as regards height will be that which is 

 actually found, namely, a distribution closely represented by the normal 

 curve ; (2) there is nothing in the values of coefficients of inheritance 

 found by Galton and Pearson which cannot be explained on the basis 

 of Mendelian inheritance. 



Castration by X-Rays.J — 01. Regaud and Th. Nogier find that it 

 is possible to sterilize, totally and finally, the testis of an adult cat by 

 use of X-rays, and without lesion of the skin. There are oviform cells 

 which survive the irradiation, but they do not continue the spermatic 

 lineage. They diminish in number gradually, and the seminal epithelium 

 remains sterile. 



Sterilization by X-Rays.§— Th. Nogier and CI. Regaud describe the 

 complete and definitive sterilization of the dog by means of X-rays. As 



* Anat. Anzeig., xxxviii. (1911) pp. 275-9 (2 figs.), 

 t Proc. R. Sqc. Edinburgh, xxxi. (1911) p. 251-6. 

 j C.R. Soc. Biol. Paris, lxx. (1911) pp. 5-7. 

 § Tom. cit., pp. 30-32. 



