170 SUMMARY OF CURRENT RESEARCHES RELATING 



Parathyroid and Thymus. — E. R. Hanson * has studied the de- 

 velopment of the accessory parathyroids and of the thymus in the rabbit. 

 The accessory parathyroids are formed by a parathyroid strand arising 

 from paratliyroid iii., and extending along the cervical portion of the 

 thymus. The accessory glands are formed in the rabbit from para- 

 thyroid IV. The thymus is a pure endodermic thymus. No thymus- 

 primordium from the second gill-cleft was found. The branchial duct 

 is of purely ectodermic origin from the second gill-cleft. 



R. Ruben t has studied the same in the guinea-pig. The thymus is 

 ecto-endodermic. The branchial duct has a similar mixed origin. A 

 parathyroid strand is formed from parathyroid ill, which gives rise to the 

 accessory parathyroids. Parathyroid iv. atrophies early. 



Thymus of Pig.+ — Agne Zotterman finds that the thymus super- 

 ficialis of the pig develops from the median pra^cervical duct, and is 

 therefore of ectodermic origin. The thymus-head arises chiefly from 

 the third visceral cleft and partly from the blind end of the median 

 praecervical duct, and is therefore in part endodermic, in part ecto- 

 dermic. Both pares have the same structure. A superficial part of the 

 praBcervical duct — the ductus prajcervicalis lateralis — -usually atrophies 

 without sharing in thymus-formation. The branchial duct in the pig 

 is a derivative of the second gill-pouch and the second gill-cleft — endo- 

 dermic in its cranial portion, ectodermic in its caudal portion. It 

 normally atrophies without sharing in thymus-formation. 



Lateral Hermaphroditism in Edible Frog.§ — S. Kuschakewitsch 

 describes a young frog of about three months after metamorphosis, 

 which he obtained from a culture of over-ripe eggs. Out of 300, all 

 were males save one — the lateral hermaphrodite. On the right side there 

 was an ovary, on the left side a testis. Lateral hermaphroditism has 

 been recorded in herring, sturgeon, several birds {Fringilla princeps, 

 Pijrrliula coccinea, and P. europaea), and in a pig, but it has not been 

 previously observed in Amphibians. 



Inheritance of Left-handedness.|] — H. E. Jordan has studied seventy- 

 eight lineages in which left-liandedness occurred, in a canvass of nearly 

 3000 individuals. He adopts the view of Wilson, that left-handedness 

 is associated with a greater development (preponderant size and weight) 

 of the right cerebral hemisphere. Gould's view that right-handedness 

 follows the generally more perfect development of the right eye, is not 

 accepted. Jordan's cases go to show that left-handedness is hereditary, 

 but the mode of inheritance remains obscure. It does not appear to 

 follow the Mendelian rule. 



Effect of Darkness on Goldfish.^ — J. Ogneff kept goldfishes for 

 over three years in complete darkness. There were marked changes in the 

 pigmentation of the skin, in the ovaries, and in the structure of the 



* Anat. Anzeig., xxxix. (1911) pp. 545-70 (10 figs.). 



+ Anat. Anzeig., xxxix. (1911) pp. 571-93 (11 figs.). 



I Anat. Anzeig., xxxviii (1911) pp. 514-30 (7 figs.). 



§ Anat. Anzeig., xxxviii. (1911) pp. 531-7 (5 figs.). 



il Amer. Breeders' Mag., ii. (1911) pp. 19-29, 113-24. 



^ Anat. Anzeig., xl. (1911) pp. 81-7 (5 figs.). 



