ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 525 



sent a sensory apparatus pertaining to the spinal cord. The same is 

 probably true in the laucelet. Since the central canal arises from an 

 ectodermic sensory plate, it is not surprising that it should retain sensory 

 cells. 



Culture of Spinal Ganglia in vitro.* — Gr. Marinesco and J. Minea 

 have continued their observations on isolated pieces of the spinal ganglia 

 of the rabbit, cat, and dog. The pieces are kept in autogenous or 

 homogeneous plasma and show some vital activity. There is an intra- 

 plasmic growth of the connective cells and of nerve fibres which originate 

 from the surviving nerve cells. There is a reaction in the interior of 

 the fragment ; prolongations of surviving cells form a pericellular or 

 periglomerular plexus, as is also seen in grafts. There are also neuro- 

 fibrillar metamorphoses in the surviving nerve cells. 



The authors have observed direct division of connective cells. The 

 nerve cells show no division, but only the formation of new outgrowths 

 and internal chemical and structural changes of neurofibrils. The neo- 

 formations sometimes show an extraordinary exuberance. Fragments of 

 cat or dog ganglion in a culture of rabbit plasma exhibit all the pheno- 

 mena which are seen in grafts. The differences of results with autogenous 

 and heterogeneous plasma are quantitative rather than qualitative. 

 Pure plasma is most suitable for the culture of ganglia, and dilution is 

 disadvantageous. A cell kept alive for twenty days with four changes 

 of plasma showed twelve outgrowths with terminal swellings — a maximum 

 exhibition of vitality. It should be noted that connective-tissue cells 

 survive more readily than nerve cells, being less differentiated. They 

 multiply and can live longer. 



Culture of Tissues.f — C. Champy discusses his experiments on the 

 culture of tissues in plasma outside of the body. The fragment of 

 tissue is plunged in the liquid plasma and kept in contact with the 

 surface. The plasma coagulates and is kept in a saturated humid 

 atmosphere at 37-38° C. The preparation is washed daily with the serum 

 of the animal which furnished the plasma. This removes waste- 

 products and the results of autolysis. 



The cells do not retain their characteristic qualities, but exhibit 

 de-differentiation. There is often a return to a blastoderm-like state on 

 the part not only of embryonic tissues but of those from the adult as 

 well. Mitosis may be seen in fragments of kidney, thyroid gland, and 

 smooth muscles, and even in Midler's fibres from the retina. 



Champy discusses in particular the behaviour of smooth muscle from 

 the bladder and the arteries. In the former the cell becomes swollen 

 around the nucleus and a mitosis occurs, and the two cells first formed 

 continue to divide, so that a series results from one smooth fibre. An 

 indifferent tissue results, but the most differentiated (fibrillar) part of 

 the original cytoplasm is left by itself and degenerates. The muscle of 

 the arteries, which is less differentiated, is even quicker in showing 



* Ariat. Anzeig., xlvi. (1914) pp. 529-47 (13 figs.). 



t Arch. Zool. Exper., liii. (1913) Notes et Revue, No. 2, pp. 42-51 (8 figs.). 



