BUMMABY OF CURBENT RESEARCHES RELATING TO 



<;tviti.s and lymph-channels of the posterior extremities and pelvic 

 regions, and open into tributaries of the posterior renal advehent veins. 

 author finds that the intercellular mesenchymal spaces have an 

 important function in initiating the development of the posterior lymph- 

 hearts. 



Occipital Region of Urodela.*— E. 8. Goodrich has studied the de- 

 velopment of this region in the head of Amblystoma. There are three 



ipital segments. The first forms no muscle and disappears early; 

 the second forms a myotome divided into dorsal and ventral portions, of 

 which the former alone persists, fusing with the myotome next behind. 

 The myotome of the third segment persists dorsal ly ; that of the first 

 trunk-segment combines- with it to form the temporal longitudinal muscle 

 supplied in the adult by the first spinal nerve. The glossopharyngeal 

 nerve belongs to the first metaotic segment, and has no ventral root. 

 To the second segment belongs the vagus root, with which seem to be 

 combined the ganglia of the next two nerves. No ventral root was 

 found in the second segment, but a ventral root occurs in the last meta- 

 otic segment in early stages of development. The first spinal issues from 

 between the skull and first neural arch as a ventral root only ; it joins 

 the second spinal to form the hypoglossal nerve supplying muscles derived 

 from ventral outgrowths of the second, third, and fourth myotomes. 

 The basilar plate of the skull is formed from a backward growth of the 

 trabecule meeting a forward growth of the base of the occipital arches. 

 It fuses with the auditory capsules and with the praeoccipital arches de- 

 veloped in the septum between the first and second myotomes. The 

 occipital arches arise in the septum between the second and third myo- 

 tomes. There is no evidence of the disappearance of segments behind 

 the vagus, and no valid objection to the view that the hind limit of the 

 skull may shift backwards or forwards in the course of phylogeny. At 

 the same time, there is no reason to suppose that the ancestors of the 

 Amphibia had more than three occipital segments, when the occipital 

 condyles became clearly defined. 



Ovarian Ovum of Proteus.j — Max Jorgensen gives a detailed and 

 beautifully illustrated account of the growth of the ovarian ovum in 

 Proteus anguineus, describing all the changes in the nucleus and in the 

 cytoplasm. Among the points discussed at length the following may be 

 noticed : the share of the chromidium in the reconstruction of the 

 chromatin after it has been " pulverized " in the second stage of growth ; 

 the formation of the curious " lamp-brush " chromosomes ; the continuity 

 of the chromosomes ; the use of the nucleoli (probably reservoirs for 

 products of metabolism and furnishing ferments useful in plasm-growth 

 and yolk-formation) ; the conditions of growth in the ovum and of yolk- 

 formation. 



Development of Gonads in Frog.}— Sergius Kuschakewitsch gives a 

 v. tv welcome detailed account of the development of ovary and testis in 

 Rana esculenta, contrasting the two at all stages. There appears to be a 



* Proc. Zool. Soc, i. (1911) pp. 101-20 (23 figs.). 



1 Festschrift Richard Hertwig, i. (1910) pp. 439-634 (23 pis.). 



; Op. cit., ii. (1910) pp. 61-224 (11 pis. and 13 figs.). 



