ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 571 



the complexity of the aggregate, wherefore organisms as we know them 

 arise only from like organisms. 



Study of Domestic Animals.* — Prof. S. H. Gage sums up an inter- 

 esting address on ' The importance and the promise in the study of the 

 domestic animals ' in the following sentences. " However necessary and 

 desirable it may have been in the past that the main energy of zoologists 

 should be employed in the description of new species, and in the making 

 of fragmentary observations upon the habits, structure, and embryology 

 of a multitude of forms, I firmly believe that necessity or even desira- 

 bility has long since passed away, and that for the advancement of 

 zoological science the work of surpassing importance confronting us is 

 the thorough investigation of a few forms from the ovum to youth, 

 maturity, and old age. And I also firmly believe that, whenever avail- 

 able, the gz-eatest good to science, and thus to mankind, will result from 

 a selection of domesticated forms for these thorough investigations." 



Use of Otoliths. j - — Herr J. Laudenbach has some experimental data 

 to offer in regard to the problem of the function of otoliths. In Siredon 

 pisciforme, with extirpation of the labyrinth on one side there were 

 rolling movements ; when the extirpation was effected on both sides 

 there were circling and whirling movements. But these disturbances 

 of equilibration did not occur when the otoliths were removed without 

 destruction of the whole labyrinth. 



Morphology of the Vertebrate Brain.} — Prof. B. Haller, as a con- 

 tinuation of his study of the brain of fishes, has made a detailed 

 investigation of the brain of Emys, with a special view to determining 

 the relation between the Keptilian and Mammalian arrangement of parts. 

 The third part of the memoir is to be devoted to a detailed comparison 

 of the Reptilian and the Mammalian brain, but the present part discusses 

 to some extent the vexed question of the homology of the commissures. 

 The author denies the suggestion that the commissura fornicata of 

 Reptiles can be homologised with the commissura superior of Ziehen in 

 Monotremes, or the secondary commissura anterior of the former with 

 the large ventral commissura anterior of the latter ; for the commissura 

 anterior of Reptiles corresponds with that of Placentalia, and the com- 

 missura fornicata of the former contains true transverse elements and 

 the first rudiment of a psalterium. If the transverse elements be 

 indicated by a, the psalterium elements by b, the elements of the 

 commissura anterior of Reptiles and Placentals by c, then the relations 

 can be indicated in the following formulae : — The commissura fornicata 

 of Reptiles = a -f- b, the commissura superior of Monotremes = b, the 

 secondary commissura anterior of Reptiles = c, the ventral commissura 

 anterior of Monotremes = a + c. It thus cannot be said that the repr 

 tilian condition, as at present existing, is a stage in the development of 

 the placental condition, and we must look to an extinct reptilian stock 

 for the common starting point of the brains of existing reptiles and 

 mammals. 



* Prnc. Amer. Ass. Adv. Sci., 48th Meeting, 1899, pp. 235-52. 

 t Pilujjer's Arch. Ges. Physiol., lxxvii. (1899) pp. 311-20. See Zool. Centralbl., 

 vii. (1900) p. 5G9. 



Morph. • Jahrb., xxviii. (1900) pp. 252-34G (5 pis.). Cf. this Journal, 1899, p. 21. 



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