230 PEOGRESS OP MICROSCOPICAL SCIENCE. 



pheral end exhibits inflammatory clianges, and the functional elements 

 suffer in a remarkable manner. The nuclei of the inter-annular 

 segments of the surrounding protoplasm increase in size, press upon 

 the parts within, and finally cut through the axis cylinder at the 

 points opposite the nuclei. By careful observation Eanvier discovered 

 that the axis cylinder is interrupted about the end of the third day after 

 section ; and it is exceedingly interesting that a complete anatomical 

 explanation should thus be furnished of the fact observed by Longet, 

 that the irritability of a divided nerve is lost from the third to the 

 fourth day. The observation of Eanvier also furnishes an additional 

 proof that the axis cylinder is the conducting element of the nerve. 

 After the fourth day the inflammatory changes on the peripheral 

 extremity of the divided nerve advance rapidly : the myeline of the 

 medullary sheath is reduced to fragments, the nuclei multiply, and 

 the vessels and fine connective tissue around the nerves participate in 

 the change, which is the very opposite of a degenerative one, probably 

 on account of the absence of all nervous control from the section 

 of the nerve on the central side. 



M. Huizinrja's Experiments on AUogenesis. — This gentleman writing 

 from Groningen, states that since a communication which was pub- 

 lished in March last, a further investigation of the subject has shown 

 him that the experiments then recorded do not yet fully prove the 

 reality of abiogenesis. His argumentation based on those experiments 

 is liable to the following objection : — 



The principal experiment (water, potassiimi-nitrate, magnesium- 

 sulphate, calcium-phosphate, glucose, and peptone) is conducted in a 

 neutral solution. In the control-experiments neutral ammonium-tartrate 

 is used as nutritious substance for the supposed germs. But this salt 

 disassociates by boiling, loses ammonia, and the reaction becomes acid. 

 When, therefore, bacteria appear in the principal experiment and not 

 in the control-experiments, this result can be explained by admitting 

 that the germs resist a temperature of 100^ in a neutral liquid, but are 

 killed by the same temperature in an acid solution. This explanation 

 agrees very satisfactorily with the fact proved by Pasteur, that an acid 

 reaction is much more deleterious to living germs than a neutral reac- 

 tion at the same temperature. 



This objection is very rational, but it does not throw over my 

 conclusion respecting the reality of abiogenesis, for the following 

 reasons : — 



It is now obvious that in the control-experiments ammonium-tar- 

 trate cannot be used, a nitrogenous body must be sought, not too com- 

 plex, that remains neutral by 100°. For this end I have found m-ea 

 to answer well. Pure m*ea is perfectly fit to furnish nitrogen to the 

 bacteria, but not to furnish them their carbon. Bacteria sown in a 

 solution of urea and mineral salts do not develop themselves, but when 

 suf^ar is added their growth goes forth rapidly. The following solu- 

 tion — 100 c.c. water, 2 grm. potassium-nitrate, 0-2 grm. magne- 

 sium-suljihate, 0-04 grm. calcium-phosphate, 1 grm. glucose, 0*5 grm. 

 urea, is eminently fit for the development of bacteria. Also a solution 

 that contains instead of the sugar and the urea, • 5 grm. peptone. 



