424 SUMMARY OF CURRENT RESEARCHES RELATING TO 



bronchia] pouches, and brings forward new arguments in support of the 

 view that lungs are homologous with the swim-bladder. 



Lens Formation in Frog.* — H. Spemann removed the primary lens- 

 forming cells, with a view to discover whether the lens and cornea are 

 formed independently of the nervous part of the eye. Retinal influence 

 was found necessary, but it was not determined whether the primary 

 lens-forming cells are differentiated as such before the cells of the eye- 

 cup use them in lens-formation. 



Early Stages of Pleuronectes cynoglossus.f — H. C. Williamson 

 describes a series of post-larval and early stages of P. cynoylossus. 

 There is a long post-larval period, and a large size is reached before the 

 bottom habitat is adopted. Sketches are given which ought to aid in 

 the diagnosis of preserved examples. 



b- Histology. 



Hydraulic Theory of Ciliary Action.^ — E. A. Schiifer describes 

 simple models which he has devised to illustrate ciliary action. The 

 conclusion to which a study of these models leads him, is that the theory 

 of the action of a cilium which assumes that the movement is caused by 

 the inflow and outflow of fluid, or, in other words, by the increase and 

 diminution of the fluid pressure, within a simply or spirally curved, 

 hollow extension of the cell, is adequate to explain the phenomenon, 

 and in the absence of any other physically possible theory, may be 

 provisionally adopted. 



Interconnections of Epidermal Cells.§ — L. Merk brings forward 

 evidence to show that there is more than mechanical connection between 

 the epidermal cells of the human skin, both inter se and with the sub- 

 jacent corium. They are attached to one another like the eggs and their 

 gelatinous envelopes in frogs' spawn. They are attached to the corium 

 as a drop of sputum to the surface to which it clings. 



Regeneration of Nerves.fl — Oskar Schultze concludes that the pro- 

 cesses of regeneration in peripheral nerves agree with those of ontogenesis. 

 The peripheral nerve arising from its special energids has the power of 

 repairing a defect by means of these same elements, namely the peri- 

 pheral neuroblasts, the nuclei of which are the so-called Schwann's 

 nuclei. The regeneration of a peripheral nerve is not merely auto- 

 genous, it is also isogenous, like that of epithelium, gland, or muscle. 

 The nerve grows and regenerates itself like a muscle. It seems from 

 the pathological results also that the neuron-theory must be given up. 

 The peripheral fibre is no cellular process with apposed ensheathing 

 cells ; it is a syncytium with innumerable " trophic " and regenerative 

 centres proper to itself. If there is a hole made in the syncytium, the 

 surfaces of the wound seek to close it up from both sides. If the hole 



• Zool. Anzeip., xxviii. (1905) pp. 419-82. 



t Rep. Fishery Board. Scotland, 1904 pp. 270-4. 



t Anal. Anzoig., xxvi. (1905) pp. 517-21 (2 figs.). 



§ RB Akad. Wiss. Wien, cxii.(1903) received 1905, pp. 899-412 (1 pl.and 1 fig.). 



|| Verb. Phys. Med. Gea. Wurzburg. xxxvii.(1905) pp. 267-9C (10 figa.). 



