292 SUAIJMARY OF CURRENT RESEARCHES RELATING TO 



" minnow," Fundulus heteroclitus, and finds that a percentage of dupli- 

 cities can be produced by adding to the sea-water (50 c.cm.) a varied 

 quantity (30-40 c.cm.) of a Gram-molecular solution (in distilled water) 

 of. acetone. In some cases butyric acid was used. The duplicities 

 seem to be due in part to lowering of the osmotic pressure of the 

 medium surrounding the eggs, this induces osmotic blastolysis of 

 the embryonic primordium in the more susceptible eggs. A second 

 factor of blastolysis— namely, chemical alteration— is also inferred. The 

 age of the egg, counting from the time of maturation, probably plays 

 a contributory part, the younger eggs being less susceptible. J. A. T. 



Development of Mammalian Notochord. — G. Carl Huber 

 {Anat. Record, 1918, 14, 217-64, 14 figs.) has studied this in the 

 guinea-pig in particular, and finds that the endoderm takes no active 

 part in the histogenesis of the head process, chordal canal, and chordal 

 plate, and that the latter becomes only partially and temporarily 

 incorporated in the endoderm. Therefore there seems no justification 

 for classing the chorda dorsalis as an endodermic derivative. Since 

 the head process — the primordium of the chordal canal and derived 

 structures— has its primordium in turn in the cranial portion of the 

 primitive node, a region of active ectodermic cell proliferation, and 

 since the chordal canal and plate retain their continuity with the 

 primitive node, which serves as a growth zone, there seems justifica- 

 tion in regarding head process— chordal canal and derived structures, 

 chordal plate and chorda dorsalis— as a derivative of the ectoderm in 

 the sense that the mesoderm is derived from the ectoderm of the 

 primitive streak region of the embryonic shield. J. A. T. 



Hermaphrodite Fowls.— Alice M. Boring and Raymond Pearl 

 {Joimi. Exfer. ZooL, 1918, 25, 1-47, 9 pis., 9 figs.) describe eight 

 cases— females with embryonic or degenerating ovaries. Three were 

 changing to a male condition in respect- to gonads, external characters, 

 and sex behaviour. There is no structural counterpart for the abnormal 

 behaviour of one hen treading another hen. Two guinea-chicken 

 hybrids had testes composed of undifferentiated tissue. Development 

 of comb, spurs and wattles does not stand in direct quantitative relation 

 to the sex of the gonad. Body shape and carriage have a general 

 relation to the sex of the gonad. The interstitial cells in the abnormal 

 fowls dealt with had no causal relation to the secondary sex characters. 

 The amount of lutear cells or pigment is in precise correlation with the 

 degree of external somatic femaleness exhibited by the individual. 

 ^ J. A. T. 



Ultimobranchial Bodies in Pig.— J. A. Badertscher (Amer. 

 Journ. Anat., 1918, 23, 89-131, 4 pis.) finds that these bodies partici- 

 pate in the formation of thyroid follicles, though the portion of the 

 gland in full-term embryos that is derived from them is small in 

 comparison with that derived from the median thyroid primordium. 

 The time of the transformation of the ultimobranchial bodies into 

 typical thyroid structures varies greatly. So does the degree of their 

 transformation. They usually become entirely embedded in the thyroid 

 gland. J. A. T. 



