60 SUMMARY OF CURRENT RESEARCHES RELATING TO 



takes place centrif ugallj by the transformation of mesenchymatic plasma- 

 strands. Schwann's nuclei arise from the nuclei of mesenchyme cells 

 whose plasma, in great part at least, is used to form fibres. The rami 

 communicantes are due to the sympathetic, and contain at first sympa- 

 thetic fibres only, afterwards spinal fibres as well. There is a sporadic 

 occurrence of sympathetic cells in the tail of the tadpole. The head 

 portion of the sympathetic develops late in the frog. It arises from a 

 secondary forward extension of the ganglionic strand into the cranial 

 region. There is really no sympathetic strand corresponding to the 

 cranial nerves. 



Early Development of Megalobatrachus.* — Dan de Lange, jun. 

 distinguishes three great events. The cephalogenesis or protogenesis 

 comprises the formation of the head, including the auditory vesicle, with 

 the exception of the parachordal mesoderm. The somatogenesis or 

 deuterogenesis comprises the formation of the anterior half of the trunk, 

 including the parachordal mesoderm of the head. The nrogenesis or 

 tritogenesis comprises the formation of the posterior half of the trunk 

 and the tail. 



Development of Eyes of Ammocoetes.t — F. K. Studnicka discusses 

 the lateral eyes or paired eyes of the larval lamprey. It is generally 

 supposed that they remain in some measure in an embryonic state, as 

 the state of lens in particular indicates. It seems, however, that in 

 quite young, free-living Ammocoetes, of a length of 10-12 mm., the 

 eyes can function as photo-receptors and as immobile " direction eyes." 

 The parietal eye is at first an unpigmented photo-receptor, but later on 

 it becomes an imperfect " direction eye." The lens of the lateral eyes 

 certainly remains small for a long time and without having any lens- 

 function. Perhaps the lens primordium had primarily some other func- 

 tion, and should be ranked in the series of plakodes. 



&• Histology. 



Structure of Blood-corpuscles. j — V. Schilling-Torgau finds that 

 ordinary erythrocytes have a complex structure, showing not only nucleus 

 and cytoplasm, but an archoplasm which shows "a vitreous body," "a 

 capsular body," and two " centres." The nucleus-like character of the 

 blood-plates is emphasized. It may be that Kurloif's secretion-like 

 bodies in the large mononuclear corpuscles of the guinea-pig are archo- 

 plasmic structures. The archoplasm is a paranuclear apparatus, other- 

 wise known as the " Dotterkern," the " reticular body," and the " Cen- 

 trophormia." 



Granular Leucocytes of Sauropsida.§— E. Max Kollmann finds that 

 these elements (apart from Mastzellen) pass through a series of stages, 

 which differ as regards cytoplasm, nucleus, and inclusions. They are 



* Anat. Anzeig., xlii. (1912) pp. 321-46 (11 figs.). 



t Anat. Anzeig., xli. (1912) pp. 561-78 (6 figs.). 



X Anat. Anzeig., xli. (Erganzungsheft) pp. 225-41 (9 figs.). 



§ Ann. Sci. Nat. (Zool.) xv. (1912) pp. 46-83 (1 pi. and 4 figs.). 



