1396.] Vegetable Physiology. 493 



extremely delicate protoplasmic structures originating directly from the 

 membrane. This mode of origin makes it still more probable that the 

 wall of the cell is only an external denser layer of plasm. Bacteria in 

 which the contents has been drawn away from the point of insertion of 

 the flagella by plasmolysis are apparently still capable of motion. 

 The flagella are either fastened to one or both poles of the cell or else 

 are scattered irregularly over the whole body. This position of the 

 flagella on the bacterial body i- constant :m<l may be used to distinguish 

 genera. In some species all of the plasma of the mother cell is not 

 used up in spore formation, but sometimes a considerable part is left in 

 the rod. In germination the spores swell up, lose their refractive 

 power, and usually open either at the pole or equatorially allowing the 

 young germ to protrude, but sometimes the wall of the spore entirely 

 deliquesces before the germ has protruded, the latter simply elongating 

 as a vegetative cell. It is not always easy to determine the charac- 

 ter of the refractive contents of bacterial cells, and in such cases abso- 

 lute demonstration of their sporiferous nature can only be had by see- 

 ing them germinate. All bacterial cells may pass into a resting state 

 when for any reason growth ceases, but such cells do not possess any 

 spore character and are only ordinary vegetative cells under conditions 

 unfavorable to growth. Arthrospores do not exist, and this term 

 should be discarded. Gonidia occur in the Chlamydobacteriacese. In 

 C/adothrLc these bodies escape from the sheath as swarm cells. In 

 Crenothriz and Phragmidiothrix the contents of the vegetative cells 

 becomes septated into Sarcina-like cubical packets, the individual 

 cells of which finally round off and escape on the opening of the sheath 

 as non-motile bodies which soon grow out into new threads. In Strep- 

 tothrix the contents of the cell breaks up into a seriesof ovoid or round 

 non-motile cells which escape from the sheath and grow wherever they 

 happen to lodge. 



This paper can be had from Wilhelm Engelmann, Leipsic, for 3 



marks, and ought to be in the hands of every working bacteriologist. 



Ekwin F. Smith. 



Ambrosia Once More.— There are two species of Xyleborus 

 which bore in orange wood, one is X /meatus and the other is really 

 undescribed, but goes well enough for the present under the name of 

 X pubescens. Both of these are associated frequently with Monarthrum 

 fasciatum and Monarthrum malt, not only in the orange but in other 

 hard wood trees of any kind, and even in the wood of wine and ale 

 casks, in which they are able to propagate their " ambrosia " as well as 

 in livino- or rather in dying trees: The ambrosia is very probably a dif- 



